Cleaning appliance

ABSTRACT

A dental cleaning appliance includes a handle, and a fluid delivery system for delivering a burst of working fluid to the teeth of a user. The fluid delivery system includes a nozzle from which the burst of working fluid is delivered to the teeth of the user. The appliance also includes a brush unit which extends at least partially about the nozzle. The brush unit includes a bristle carrier and a plurality of bristles mounted on the bristle carrier. A drive unit drives the movement of the bristle carrier relative to the nozzle.

REFERENCE TO RELATED APPLICATIONS

This application claims the priority of United Kingdom Application Nos.1508362.9 and 1508369.4, both of which were filed May 15, 2015, and theentire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a cleaning appliance. The cleaningappliance is preferably a handheld cleaning appliance, and is preferablya surface treating appliance. In preferred embodiments of the invention,the appliance is a dental cleaning appliance. In a preferred embodiment,the appliance is an electric toothbrush having a fluid delivery systemfor delivering a fluid to the teeth of the user. This fluid may betoothpaste, or a fluid for improved interproximal cleaning.Alternatively, the appliance may not include any bristles or otherelements for brushing teeth, and may be in the form of a dedicatedinterproximal cleaning appliance. The invention also relates to acleaning tool for use with a dental cleaning appliance, and to a handlefor use with a dental cleaning appliance.

BACKGROUND OF THE INVENTION

Electric toothbrushes generally comprise a cleaning tool which isconnected to a handle. The cleaning tool comprises a stem and a brushhead bearing bristles for brushing teeth. The brush head comprises astatic section which is connected to the stem, and at least one moveablesection which is moveable relative to the static section, for examplewith one of a reciprocating, oscillating, vibrating, pivoting orrotating motion, to impart a brushing movement to bristles mountedthereon. The stem houses a drive shaft which couples with a transmissionunit within the handle. The transmission unit is in turn connected to amotor, which is driven by a battery housed within the handle. The driveshaft and the transmission unit convert rotary or vibratory motion ofthe motor into the desired movement of the moveable section of the brushhead relative to the static section of the brush head.

It is known to incorporate into an electric toothbrush an assembly forgenerating a jet of fluid for interproximal cleaning. For example, U.S.Pat. No. 8,522,384 describes an electric toothbrush in which the handleof the toothbrush defines a fluid chamber for storing a liquid such aswater, and a slidable cover for enabling the fluid chamber to beaccessed for replenishment by a user. A fluid path connects the fluidchamber to a nozzle located on a static portion of the brush head. Apump located within the fluid path is actuated upon user operation of anactuator on the handle to pump fluid from the fluid chamber to thenozzle for release under pressure from the nozzle.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a dental cleaningappliance comprising a handle, a fluid delivery system for delivering aburst of working fluid to the teeth of a user, at least part of thefluid delivery system being moveable relative to the handle as theappliance is moved along the teeth of the user, a sensor for providingan output which varies with movement of said at least part of the fluiddelivery system relative to the handle, and a control circuit foractuating the delivery of working fluid to the teeth of the userdepending on the output from the sensor.

A part of the fluid delivery system which is moveable relative to thehandle preferably comprises a nozzle from which the burst of workingfluid is delivered to the teeth of a user. The nozzle preferably extendsalong a nozzle axis, which passes through a fluid outlet located at thetip of the nozzle. The nozzle axis may be aligned generally orthogonalto the longitudinal axis of the handle.

The nozzle is preferably formed from resilient material, such as anelastomeric material or a rubber.

The nozzle may be moveable relative to the handle in such a manner thatthe fluid outlet can move relative to the nozzle axis. For example, thenozzle may be configured to bend. For example, as the nozzle is movedalong the teeth of a user during use of the appliance, the tip of thenozzle may deflect relative to the base of the nozzle, and especiallywhen the nozzle engages a side of a tooth after having entered aninterproximal gap. This deflection of the nozzle relative to the handlemay cause the output from the sensor to vary, in response to which thecontrol circuit may actuate the delivery of a burst of working fluid tothe teeth of the user to dislodge matter located within the gap.

Alternatively, the nozzle may be moveable relative to the handle in adirection which extends generally parallel to or generally along thenozzle axis. The nozzle is preferably biased for movement relative tothe handle in such a direction that the nozzle is urged against a user'steeth during use of the appliance. As the nozzle enters an interproximalgap as the nozzle is moved along the user's teeth, this movement of thenozzle relative to the handle causes the output from the sensor to vary,in response to which the control circuit actuates the delivery of aburst of working fluid to the teeth of the user to dislodge matterlocated within the gap.

The sensor may be arranged to detect directly the movement of the nozzlerelative to the handle. For example, the sensor may be located adjacentto the nozzle. Alternatively, the sensor may be arranged to detectmovement of a component which is connected to, and moveable with, thenozzle. For example, an arm may be connected to the nozzle, and thesensor may be arranged to detect movement of the arm relative to thehandle.

A part of the fluid delivery system which is moveable relative to thehandle preferably comprises a fluid conduit for conveying the burst ofworking fluid to the nozzle. The nozzle is preferably moveable with thefluid conduit. For example, the fluid conduit may be connected directlyto the nozzle. As an alternative, the end of the fluid conduit mayengage or about the base of the nozzle so that the nozzle is pushedalong the nozzle axis in response to movement of the fluid conduitrelative to the handle.

The nozzle is preferably biased for movement relative to the handle in adirection which urges the nozzle against a user's teeth during use ofthe appliance. As mentioned above, the nozzle may be connected to anarm, and that arm may be biased for movement relative to the handle in adirection which urges the nozzle against a user's teeth during use ofthe appliance. For example, the arm may be urged to move in thatdirection by a resilient member which engages the arm. Alternatively,the arm may be deformed elastically in such a manner that relaxation ofthe arm urges the nozzle against the user's teeth. In this case, thefluid conduit moves with the nozzle as it is urged towards the user'steeth.

In a preferred embodiment, the fluid conduit is biased for movementrelative to the handle in a direction which urges the nozzle against auser's teeth during use of the appliance. This fluid conduit may thusserver to bias the nozzle for movement relative to the handle in such adirection that the nozzle is urged against a user's teeth during use ofthe appliance. As discussed above, the nozzle may be connected to theend of the fluid conduit so that it moves with the fluid conduitrelative to the handle. Alternatively, the nozzle may be secured to abody of the appliance by resilient means, for example a resilientannular flange extending outwardly from the nozzle, which urges thenozzle against the end of the fluid conduit so that it moves with thefluid conduit as the fluid conduit moves relative to the handle. Thisflange may also provide a seal between the nozzle and the body whichinhibits the ingress of ejected working fluid or other material into thebody of the appliance from around the nozzle.

The fluid conduit may be moveable relative to the handle in one of anumber of different ways. For example, the fluid conduit may beslidable, rotatable or otherwise translatable relative to the handle.Alternatively, the fluid conduit may be extendable or expandable.

In a second aspect, the present invention provides a dental cleaningappliance comprising a handle, and a fluid delivery system comprising anozzle for delivering a burst of working fluid to the teeth of a user,and a fluid conduit for conveying working fluid to the nozzle, the fluidconduit being moveable relative to the handle, the nozzle being moveablewith the fluid conduit, the fluid conduit being biased for movement in adirection which urges the nozzle against a user's teeth during use ofthe appliance.

In a preferred example, the fluid conduit is moveable relative to thehandle about an axis. The fluid conduit is preferably pivotable aboutthe axis. This axis is preferably substantially orthogonal to thelongitudinal axis of the handle. The axis is preferably angled to thenozzle axis, and is more preferably substantially orthogonal to thenozzle axis.

The fluid conduit preferably has a rigidity which is such that the fluidconduit does not deform, bend or kink as the fluid conduit movesrelative to the handle or as the nozzle is urged against the teeth ofthe user during use of the appliance. The fluid conduit is preferablyformed from one of metallic and plastics material. However, if an arm isused to bias the nozzle towards the user's teeth, the fluid conduit maybe formed from a more flexible material to allow the fluid conduit tomove freely relative to the handle.

The fluid conduit is preferably biased for movement relative to thehandle by a resilient member. The resilient member may engage acomponent to which the fluid conduit is connected. For example, thenozzle may be connected to an arm, and that arm may be biased formovement relative to the handle. As the arm moves relative to thehandle, the fluid conduit may move relative to the handle, preferablyabout an axis. Alternatively, the resilient member may engage the fluidconduit. The resilient member preferably exerts a force on the fluidconduit, or the arm, which is of a sufficient magnitude to allow thenozzle to move, against the biasing force of the resilient member, as itis pressed against the user's teeth, and without exerting an excessiveforce on the teeth which is uncomfortable for the user.

The resilient member may be located between the body and the fluidconduit, so as to urge the fluid conduit to move about the axis in adirection which urges the nozzle against a user's teeth during use ofthe appliance. The resilient member may be in the form of a spring oranother elastic element. The resilient member may engage the fluidconduit directly, or it may engage a component of the appliance which isconnected to the fluid conduit and moveable therewith. Such a componentmay be a support for supporting the fluid conduit for movement relativeto the handle, or an arm connected to the fluid conduit.

In a preferred embodiment, the resilient member forms a part of thefluid delivery system, and is preferably in the form of a resilientfluid conduit which is connected to the pivotable, or moveable, fluidconduit. That resilient fluid conduit may be twisted, bent, compressedor otherwise deformed so as to exert a force on the pivotable fluidconduit which urges it to move relative to the handle in a directionwhich urges the nozzle against a user's teeth during use of theappliance.

Thus, the fluid delivery system may comprise a nozzle from which theburst of working fluid is delivered to the teeth of a user, a relativelyrigid fluid conduit which is pivotable about an axis, and a relativelyflexible, resilient fluid conduit for urging the pivotable fluid conduitto pivot about the axis in a direction which urges the nozzle against auser's teeth during use of the appliance.

The pivotable fluid conduit is preferably located between the nozzle andthe resilient fluid conduit. For example the resilient fluid conduit maybe connected to one end of the pivotable fluid conduit, with the nozzlebeing connected to, or otherwise engaging, the other end of thepivotable fluid conduit.

The pivotable fluid conduit preferably has a plurality of sections. Forexample, the fluid conduit may have a first section and a second sectionwhich extends in a different direction to the first section. In otherwords, the fluid conduit is preferably non-linear. The resilient fluidconduit is preferably connected to the first section. The second sectionmay be angled to the first section, and may be substantially orthogonalto the first section. Alternatively, the second section may be curved.The nozzle is preferably connected to, or otherwise engages, the secondsection, and so at least part of the second section is preferablysubstantially collinear with the nozzle. Where the second section iscurved, at least an end portion of the second section, which engages thenozzle, may be collinear with the nozzle. The first section ispreferably straight, and is preferably longer than the second section,and so the pivotable fluid conduit may be generally L-shaped.

The sensor is preferably arranged to provide an output which varies withmovement of a moveable part of the fluid delivery system relative to thehandle, and so, in this embodiment, with movement of one of the nozzle,the pivotable fluid conduit, and the resilient fluid conduit. The sensormay be in the form of a motion detector.

The sensor may be arranged to detect motion of a moveable part of thefluid delivery system directly. For example, the sensor may be in theform of a light detector, such a camera or a light sensor, for receivinglight reflected from the moveable part of the fluid delivery system.Alternatively, the moveable part of the fluid delivery system may beformed from magnetic material, with the sensor being arranged to detectthe movement of that magnetic part of the fluid delivery system from thevariation in the magnetic field experienced by the sensor. For example,the sensor may be a Hall effect sensor.

Alternatively, the sensor may be arranged to detect motion of acomponent which is moveable with the moveable part of the fluid deliverysystem. That component may comprise a light reflective component orlight emitting component. Alternatively, the component may comprise adeformable member which is connected to the moveable part of the fluiddelivery system, and the sensor may be arranged to detect thedeformation of that deformable member. For example, the deformablemember may be in the form of an elastic rod which is connected to themoveable part of the fluid delivery system, and the sensor may be in theform of a strain gauge for outputting a signal which varies with thestrain on the deformable member.

Preferably, the component comprises a magnet, and the sensor ispreferably arranged to detect the movement of the magnet from thevariation in the magnetic field experienced by the sensor as the magnetmoves relative to the sensor. The magnet may be connected directly tothe moveable part of the fluid delivery system. Alternatively, tofacilitate assembly the magnet may be connected to a component which isitself connected to, or carried by, a moveable part of the fluiddelivery system. For example, the appliance may comprise a support forsupporting a moveable part of the fluid delivery system for movementrelative to the handle. The support is preferably moveable relative tothe handle with the moveable part of the fluid delivery system. In apreferred embodiment, the support is connected to the pivotable fluidconduit.

The magnet may be connected directly to the support. However in apreferred embodiment the appliance comprises an arm which connected tothe support for movement therewith, with the magnet being connected to,or defining, part of the arm. The magnet is preferably connected to afree end of the arm.

The arm is preferably moveable relative to the support. The armpreferably has a first end which is connected to the support formovement therewith, and a second end which is remote from the first end.A magnet, or magnetic material, is preferably located at the second endof the arm. The arm is preferably pivotably moveable relative to thesupport about a second pivot axis. The second pivot axis may be locatedat the first end of the arm, or it may be located between the ends ofthe arms, with the distance between the second pivot axis and the secondend of the arm being greater than the distance between the second pivotaxis and the first end of the arm. As a result, for a given rotation ofthe arm about the second pivot axis, which rotation results from thepivoting movement of the support relative to the handle, the extent ofthe movement of the second end of the arm about the second pivot axis isgreater than the extent of the movement of the support relative to thehandle.

This can enable relatively small movements of the moveable part of thefluid delivery system relative to the handle to be converted intorelatively large movements of the second end of the arm relative to thehandle. This can facilitate the detection of the movement of themoveable part of the fluid delivery system relative to the handle, andcan enable the sensor to be located at a convenient location within theappliance for detecting the movement of the second end of the arm. Forexample, the sensor may be located in the handle of the appliance tofacilitate its connection to the control circuit, which is alsopreferably located in the handle of the appliance. A battery forsupplying power to the control circuit is also preferably located in thehandle of the appliance. The battery is preferably a rechargeablebattery.

The appliance preferably comprises a head, and a stem extending betweenthe head and the handle. The nozzle preferably protrudes outwardly fromthe head. The resilient fluid conduit is preferably located in the stem.The pivotable fluid conduit thus extends between the stem and the head.In a preferred embodiment, the first section of the pivotable fluidconduit is located in the stem, and the second portion of the pivotablefluid conduit is located in the head.

The nozzle is preferably moveable relative to the head. The nozzle ispreferably biased for movement relative to the head in a direction whichextends away from the head.

The nozzle is preferably moveable between a distal position and aproximal position relative to the head. The nozzle is preferably biasedfor movement towards the distal position. The control circuit ispreferably configured to actuate the delivery of working fluid to theteeth of the user in response to movement of the nozzle to, or from, thedistal position.

The control circuit may be configured to actuate the delivery of workingfluid to the teeth of the user depending on the magnitude of the outputfrom the sensor. Preferably, the control circuit is configured toactuate the delivery of working fluid to the teeth of the user dependingon the rate of change of the output from the sensor. The output from thesensor is preferably in the form of a voltage.

In a preferred embodiment, the control circuit is configured to samplethe output from the sensor at predetermined intervals to provide aseries of sampled sensor outputs, S. For example, the predeterminedinterval may be in the range from 5 to 25 ms, and in a preferredembodiment is 10 ms. The rate of change, Sr, of the sampled sensoroutputs S is calculated from the difference between consecutive sampledsensor outputs S. In the preferred embodiment, Sr is calculated every 10ms.

The control circuit is further configured to determine an average rateof change of the sensor output, Sa, by calculating the average value ofthe n most recent values of Sr. The integer n is preferably in the rangefrom 5 to 40, and in the preferred embodiment is 10. A value for Sa isthus also calculated every 10 ms. From the value of Sa, it can bedetermined whether, over a time period of 100 ms, the nozzle is tendingto move towards the distal position, move away from the distal position,or remain in a relatively stationary position relative to the handle,for example, at the distal position.

The control circuit is preferably configured to actuate the delivery ofworking fluid to the teeth of the user depending on the value of Sa. Thecontrol circuit may be configured to actuate the delivery of workingfluid to the teeth of the user depending on the variation with time ofthe value of Sa. For example, the control circuit may be configured toactuate the delivery of working fluid to the teeth of the user when (i)the value of Sa has risen above, or fallen below, a first pre-setthreshold value—which is indicative of the nozzle moving towards itsdistal position—and (ii) the value of Sa has subsequently fallen below,or risen above, a second pre-set threshold value—which is indicative ofthe nozzle being located within an interproximal gap, or moving awayfrom an interproximal gap towards its proximal position.

An advantage associated with the actuation of the delivery of workingfluid to the teeth of the user in response to movement of the nozzleaway from the distal position is that the working fluid is not ejectedfrom the nozzle when the implement is moved away from the teeth of theuser, for example at the end of a cleaning operation.

As mentioned above, the pivotable fluid conduit is preferably moveableabout a pivot axis. As the nozzle moves between its distal and proximalpositions relative to the head, the nozzle thus preferably moves along acurved path, preferably in the shape of an arc which has a centre whichis located on the pivot axis of the fluid conduit. The extent of theangular movement of the tip of the nozzle about the pivot axis ispreferably in the range from 1 to 5°. In a preferred embodiment, the tipof the nozzle moves about the pivot axis by an angle of approximately2.5° as the nozzle moves from the distal position to the proximalposition. Thus, the nozzle may be considered to be biased for movementin a plane containing the nozzle axis, and along a curved or circularpath located within that plane. When the nozzle is in its distalposition, the nozzle axis is preferably aligned at an angle of 90° tothe longitudinal axis of the handle.

To facilitate the movement of the nozzle along the teeth of user duringuse of the appliance, the head preferably comprises means for engagingthe teeth of the user, with the nozzle being moveable relative to theengaging means as it moves between its distal and proximal positions.For user comfort, the engaging means may be formed from resilient orelastomeric material. The engaging means may have a substantially flatupper surface, a curved upper surface, or a stepped upper surface. Forexample, the engaging means may have a concave upper surface. When thenozzle is in its distal position relative to the head, the tip of thenozzle preferably protrudes outwardly beyond at least some of theengaging means so that, when the nozzle is pressed against a user'steeth, the nozzle moves away from the distal position and towards theproximal position.

The appliance may be in the form of a dedicated interproximal cleaningappliance for cleaning between the gaps in the user's teeth. As thenozzle is moved along the teeth of the user, the entry of the nozzleinto a gap between adjacent teeth is detected through the variation inthe output from the sensor resulting from the movement of the magnetrelative to the sensor. For such an appliance, the engaging means maycomprise a single resilient member which surrounds the nozzle.Alternatively, the engaging means may comprise a plurality of resilientmembers arranged adjacent to the nozzle. The resilient members may belocated on opposite sides or ends of the head, or arranged about thenozzle. For example, the resilient members may be arrangedcircumferentially about the nozzle. The resilient member(s) may beformed from elastomeric material.

Alternatively, the appliance may be in the form of a toothbrush whichhas the additional function of improved interproximal cleaning throughthe emission of a burst of working fluid into the interproximal gap.Where the appliance is in the form of a toothbrush, the engaging meanspreferably comprises a plurality of bristles. The bristles arepreferably arranged around the nozzle, and may be arrangedcircumferentially about the nozzle.

The plurality of bristles may be attached to a static section of thehead, which section is not moveable relative to the handle.Alternatively, or additionally, a plurality of bristles may be attachedto a moveable section of the head, which section is moveable relative tothe handle. In a preferred embodiment, the appliance comprises a brushunit comprising a bristle carrier and a plurality of bristles mounted onthe bristle carrier, with the bristle carrier being moveable relative tothe handle. The nozzle is preferably biased for movement relative to thebrush unit in a direction extending away from the brush unit.

In addition to the movement of the nozzle relative to the brush unit,the brush unit is preferably moveable relative to the nozzle. Themovement of the brush unit relative to the nozzle, to enable the ends ofthe bristles to be swept over the surfaces of the teeth of the user, maythus be independent from the movement of the nozzle relative to thehandle to cause a burst of working fluid to be delivered to the teeth ofthe user. This can prevent any spurious or otherwise undesired actuationof the delivery of working fluid to the teeth of the user resulting frommovement of the bristles relative to the handle.

The bristle carrier may translate, rotate, pivot or vibrate relative tothe nozzle. In a preferred embodiment, the bristle carrier is arrangedto orbit about the nozzle, and preferably about the axis of the nozzlewhen the nozzle is in its distal position. The brush unit preferablyextends at least partially about the nozzle. For example, the bristlecarrier may be curved or partially annular, for example C-shaped, so asto extend partially about the nozzle. Alternatively, the bristle carriermay be annular in shape, or otherwise shaped to surround the nozzle. Forexample, the bristle carrier may comprise an aperture through which thenozzle protrudes.

In a third aspect, the present invention provides a dental cleaningappliance comprising a handle, a fluid delivery system for delivering aburst of working fluid to the teeth of a user, the fluid delivery systemcomprising a nozzle from which the burst of working fluid is deliveredto the teeth of the user, a brush unit comprising a bristle carrier anda plurality of bristles mounted on the bristle carrier, the brush unitextending at least partially about the nozzle, and a drive unit fordriving movement of the bristle carrier relative to the nozzle.

The appliance preferably includes a drive unit for driving the movementof the bristle carrier, and a transmission unit for converting a rotarymotion generated by the drive unit into an orbital motion of the bristlecarrier. The drive unit is preferably located in the handle of theappliance. The drive unit preferably comprises a motor, which is poweredby the battery, and a first set of gears.

The transmission unit preferably comprises a second set of gears, acrank, and a connecting rod which connects the bristle carrier to thecrank. The connecting rod is preferably located within the stem. Thepivotable, or moveable, fluid conduit is also preferably located withinthe stem, and so this fluid conduit is preferably located alongside theconnecting rod.

The fluid delivery system may comprise a source of pressurized workingfluid and a valve. The source of pressurized working fluid and the valveare preferably located in the handle of the appliance. The controlcircuit is preferably configured to open the valve for a period of timedepending on the output from the sensor. The valve is preferably openedfor a time period which is sufficient to allow a burst of pressurizedworking fluid having a selected volume to pass from the source to thenozzle for delivery to the teeth of the user. This time period ispreferably less than 1 second, more preferably less than 0.5 seconds,and even more preferably less than 0.25 seconds.

The valve is preferably a solenoid valve.

The working fluid is preferably a liquid working fluid, and ispreferably water. Where the working fluid is a liquid working fluid, thesource of pressurized working fluid is preferably in the form of ahydraulic accumulator. The hydraulic accumulator is preferably one of aspring-type accumulator, and a gas-charged accumulator. The accumulatorpreferably comprises a fluid chamber for storing working fluid underpressure. The accumulator is preferably arranged to store working fluidat a pressure in the range from 4 to 7 bar. The fluid chamber preferablyhas a capacity in the range from 0.1 to 1 ml.

The use of a combination of a hydraulic accumulator and a solenoid valvecan allow bursts of working fluid of substantially uniform pressure andduration to be delivered to the teeth of a user.

The fluid delivery system preferably comprises a pump for supplyingworking fluid to the accumulator when the solenoid valve is in a closedposition. The pump is arranged to draw working fluid through a fluidinlet. The pump is preferably in the form of a diaphragm pump.Alternatively, the pump may be a piston pump. A first one-way valve ispreferably located between the fluid inlet and the pump to preventworking fluid from returning to the fluid inlet. A second one-way valveis preferably located between the pump and the accumulator to preventworking fluid from returning to the pump from the accumulator.

In a fourth aspect, the present invention provides a dental cleaningappliance comprising a fluid delivery system comprising a fluid inlet, apump for drawing a working fluid through the fluid inlet, a hydraulicaccumulator for receiving working fluid from the pump, a nozzle having afluid outlet, and a valve located between the accumulator and thenozzle, the valve having an open position for enabling the accumulatorto deliver a burst of working fluid to the nozzle and a closed positionfor enabling the accumulator to be replenished under the action of thepump, and a control circuit for actuating the pump and for controllingthe position of the valve.

The capacity of the fluid chamber of the accumulator may besubstantially the same as the volume of a single burst of working fluid.For example, the fluid chamber may have a capacity of around 0.25 ml,and a single burst of working fluid may have a volume of around 0.25 ml.In this case, the accumulator is substantially emptied following thedelivery of a single burst of working fluid to the nozzle, and sorequires replenishment before another burst of working fluid can bedelivered. The time taken to replenish the accumulator is preferably inthe range from 0.25 to 1 second, during which time the control circuitis preferably arranged to inhibit the delivery of working fluid to thenozzle, irrespective of the output from the sensor.

Alternatively, the capacity of the fluid chamber of the accumulator maybe larger than the volume of a single burst of working fluid. Forexample, the fluid chamber may have a capacity of around 0.75 ml, and asingle burst of working fluid may have a volume of around 0.25 ml. Inthis case, the solenoid valve is held in an open position by the controlcircuit for a time required for a selected volume of working fluid to beejected from the accumulator. For example, the solenoid valve may beheld in an open position for a time period in the range from 1 to 100ms, more preferably in the range from 5 to 50 ms, and in a preferredembodiment for a time period of 30 ms, to allow a single burst ofworking fluid having a volume of 0.25 ml to be delivered to the nozzle.

In this case, the accumulator is substantially emptied following thedelivery of three bursts of working fluid to the nozzle, although thetime required to replenish the accumulator following the delivery ofthose bursts of working fluid to the nozzle will increase, for exampleto a time period in the range from 0.75 to 3 seconds, in view of thelarger capacity of the accumulator. As opposed to increasing thecapacity of the fluid chamber of the accumulator, the volume of a singleburst of working fluid may be decreased. For example, the fluid chambermay have a capacity of around 0.25 ml, and a single burst of workingfluid may have a volume of around 0.08 ml. In this case, the solenoidvalve is held in an open position by the control circuit for a timerequired for a selected volume of working fluid to be ejected from theaccumulator, for example for a time period of around 10 ms, to allow asingle burst of working fluid having a volume of 0.08 ml to be deliveredto the nozzle. In this latter case, again the accumulator issubstantially emptied following the delivery of three bursts of workingfluid to the nozzle, but the time required to replenish the accumulatorfollowing the delivery of those bursts of working fluid to the nozzlewill remain in the range from 0.25 to 1 second.

As discussed above, the control circuit may be arranged to deliver asingle burst of working fluid depending on the output from the sensor.However, the control circuit may be arranged to deliver a series ofbursts of working fluid depending on the output from the sensor. Withina series, the time period between successive bursts of working fluid ispreferably substantially equal, preferably in the range from 1 to 25 ms,and more preferably in the range from 2 to 10 ms, so that the entireseries of bursts may be delivered to a single interproximal gap. Thiscan allow for a slight variation in the position of the tip of thenozzle relative to interproximal gap between each successive burst, andso potentially improving the removal of material from within theinterproximal gap.

In a fifth aspect, the present invention provides a dental cleaningappliance comprising a handle, a fluid delivery system for deliveringworking fluid to the teeth of a user, and a control circuit foractuating the delivery of working fluid to the teeth of the userdepending on a received input, wherein, for each input, the controlcircuit is arranged to actuate the delivery of a series of bursts ofworking fluid to the teeth of the user. The input may be generated by asensor. Alternatively, the input may be generated in response to a useraction on the appliance, for example, the operation of a button of theappliance.

The number of bursts within a series is preferably in the range from twoto ten. The volume of working fluid delivered to the teeth of a user ina series of bursts is preferably in the range from 0.1 to 1 ml. Within aseries of bursts, each burst of working fluid preferably hassubstantially the same, which is preferably in the range from 0.05 to0.5 ml, and more preferably in the range from 0.05 to 0.25 ml.

The capacity of the fluid chamber of the accumulator may besubstantially the same as the volume of working fluid which is ejectedfrom the appliance in a single series of bursts of working fluid. Forexample, the fluid chamber may have a capacity of around 0.25 ml, and asingle series of bursts of working fluid may eject a volume of workingfluid of around 0.25 ml. In this case, the fluid chamber requiresreplenishment before another series of bursts of working fluid can bedelivered. Alternatively, the capacity of the fluid chamber of theaccumulator may be greater than the volume of working fluid which isejected from the appliance in a single series of bursts of workingfluid. For example, the fluid chamber may have a capacity of around 0.75ml, and a single series of bursts of working fluid may have a volume ofaround 0.25 ml. In this case, the fluid chamber requires replenishmentfollowing the delivery of three series of bursts of working fluid.

The appliance preferably comprises a fluid reservoir for storing workingfluid, preferably a liquid working fluid, and from which working fluidis supplied to the fluid delivery system. The fluid reservoir preferablyhas a capacity in the range from 5 to 50 ml. For example, a fluidreservoir having a capacity of 25 ml, used in combination with anaccumulator having a fluid capacity of 0.25 ml, can supply a sufficientquantity of working fluid to the accumulator to allow up to 100 bursts,or 100 series of bursts, of 0.25 ml of working fluid to be delivered tothe teeth of a user.

The fluid reservoir is preferably refillable. The fluid reservoir thuspreferably comprises a fluid port through which the fluid reservoir maybe replenished with working fluid by the user. The fluid port may belocated in a wall which delimits the fluid reservoir, or it may belocated remotely from the fluid reservoir and placed in fluidcommunication with the fluid reservoir by a fluid conduit which extendsfrom the fluid port to the fluid reservoir.

The control circuit may be configured to generate an alert to advise theuser that the fluid reservoir requires replenishment. For example, theaccumulator may comprise a sensor for providing a signal to the controlcircuit which is indicative of the volume of working fluid stored withinthe accumulator. The sensor may comprise a pressure sensor for providinga signal which is indicative of the pressure of working fluid storedwithin the accumulator. For example, the sensor may output a signal tothe control circuit when the pressure within the accumulator hasexceeded a pre-set threshold value. Alternatively, the sensor may be inthe form of a sensor which contacts a part of the accumulator, such as apiston or a diaphragm, which moves as the accumulator fills with workingfluid. For example, that sensor may output a signal to the controlcircuit when the diaphragm has contacted the sensor. Duringreplenishment of the accumulator following the delivery of working fluidto the nozzle, the control circuit may be configured to de-activate thepump upon receipt of such a signal. If such a signal is not receivedwithin a predetermined time period, for example, in the range from 0.5to 2 seconds, following actuation of the pump, this can be indicative ofthere being insufficient working fluid stored within the fluid reservoirto enable the accumulator to be fully replenished. In this case, thecontrol circuit is preferably configured to, following the expiration ofthat time period, generate an alert to advise the user that the fluidreservoir requires replenishment. That alert may be in the form of avisual alert generated on a display of the appliance, or an audiblealert.

The handle of the appliance may comprise the fluid reservoir. Forexample, the fluid reservoir may be fully contained within the body ofthe handle. Alternatively, an external wall of the handle may at leastpartially delimit the fluid reservoir. At least part of that externalwall may be transparent to allow a user to see the volume of workingfluid contained within the fluid reservoir. To replenish such a fluidreservoir, the fluid port may be exposed manually by the user throughmoving a cover on the body of the handle, or through removing a bung orother closure device from the fluid port.

The fluid reservoir may be housed within the stem. As above, an externalwall of the stem may at least partially delimit the fluid reservoir, andat least part of that external wall may be transparent to allow a userto see the volume of working fluid contained within the fluid reservoir.

As an alternative to housing the fluid reservoir within the stem, thefluid reservoir may be connected to the stem so as to be locatedexternally of the stem. This can allow the fluid reservoir to bedetached from the stem for replenishment or replacement as required.Alternatively, the fluid reservoir may be partially delimited by anexternal wall which is connected to the stem. Again, at least part ofthat external wall may be transparent to allow a user to see the volumeof working fluid contained within the fluid reservoir.

To maximize the capacity of the fluid reservoir and to provide for arelatively even weight distribution about the longitudinal axis of theappliance, the fluid reservoir preferably extends about, or surrounds,the stem.

The appliance preferably comprises a cleaning tool connected to thehandle. The cleaning tool comprises the nozzle of the fluid deliverysystem. The cleaning tool preferably comprises the head and the stem ofthe appliance.

The cleaning tool is preferably detachably connected to the handle. Thiscan allow the cleaning tool to be replaced, for example when anon-refillable fluid reservoir has become depleted, or when the bristlesand/or the nozzle of the appliance have become worn. This can also allowa different cleaning tool to be connected to the handle, for example foruse by a different user.

In a sixth aspect, the present invention provides a dental cleaningappliance comprising a handle, and a cleaning tool detachably connectedto the handle, the cleaning tool comprising a nozzle for delivering aburst of working fluid to the teeth of a user, a stem extending betweenthe handle and the nozzle, and a fluid reservoir for storing workingfluid, the fluid reservoir being connected to and extending around thestem.

The fluid reservoir preferably comprises an external wall whichsurrounds part of the stem. That part of the stem is preferably locatedadjacent to the handle of the appliance. At least part of that externalwall is preferably transparent, and is preferably formed fromtransparent plastics material to allow a user to see the volume ofworking fluid within the fluid reservoir. In a preferred embodiment, theexternal wall is a single molded component formed from transparentmaterial.

The external wall of the fluid reservoir preferably has one of a curvedshape, a convex shape, and a faceted shape. The external wall may have acurvature which is one of ellipsoidal, spheroidal and spherical.

As mentioned above, the appliance may comprise a fluid port throughwhich the fluid reservoir is replenished with working fluid. The fluidport may be permanently exposed, with a bung or other closure devicebeing removably located within the fluid port to inhibit leakage ofworking fluid from the fluid reservoir through the fluid port.Preferably, the fluid port is located on an external collar, which ismoveable relative to the handle between a first position in which thefluid port is exposed to allow the fluid reservoir to be replenished,and a second position in which the fluid port is occluded. This canenable the fluid port to be easily and rapidly exposed by the user toreplenish the fluid reservoir.

In a seventh aspect, the present invention provides a dental cleaningappliance comprising a handle, a fluid reservoir for storing a workingfluid, a fluid delivery system for receiving working fluid from thefluid reservoir, and for delivering a burst of working fluid to theteeth of a user, and an external collar comprising a fluid port, thecollar being moveable relative to the handle between a first position inwhich the fluid port is exposed to allow the fluid reservoir to bereplenished, and a second position in which the fluid port is occluded.

When the collar is in the second position, the fluid port may be in aposition in which it engages a seal which inhibits the leakage ofworking fluid through the fluid port. This seal may be located on aninternal surface of a wall or other part of the handle which faces thefluid port when the collar is in the second position. Preferably, whenthe collar is in the second position, the fluid port is connected to thefluid delivery system so that working fluid may be supplied to the fluiddelivery system through the fluid port rather than from an additionalfluid port.

The collar may be slidable relative to the handle. Preferably, thecollar is rotatable relative to the handle, and preferably about thelongitudinal axis of the handle. The collar may be connected to the bodyof the handle for movement relative to the body of the handle. In apreferred embodiment, the collar is connected to the cleaning tool ofthe appliance, and is preferably located about the stem. The collar mayrotate about the longitudinal axis of the stem. The collar may have oneof a curved shape, a convex shape, and a faceted shape, and may have acurvature which is one of ellipsoidal, spheroidal and spherical.

The collar may be separate from the fluid reservoir. The fluid port maybe connected to the fluid reservoir by a flexible conduit having an endwhich is connected to the fluid port and which moves with the collar asit is moved between the first position and the second position.

Alternatively, the collar may at least partially delimit the fluidreservoir, and may form part of the external wall of the reservoir.Thus, at least part of the external wall of the fluid reservoir may moverelative to the handle as the collar portion of the external wall ismoved between the first position and the second position. Seals may beplaced between the moving part of the fluid reservoir and the otherparts of the fluid reservoir, relative to which that part of the fluidreservoir moves, to inhibit the leakage of working fluid from betweenthose parts of the fluid reservoir. However, in a preferred embodiment,the entire fluid reservoir, including the collar, external wall and anyother component which delimits the fluid reservoir, is moveable relativeto the handle.

For example, the fluid reservoir may comprise an inner wall which isconnected to the external wall, and which moves with the external wallrelative to the handle. The inner wall may be annular or tubular inshape, and located around the stem so as to provide a sleeve whichsurrounds the stem. The ends of the inner wall may be joined, forexample using a welding technique or using an adhesive, to the externalwall.

The entire inner wall, along with the external wall, may be formed fromrelatively rigid plastics material, so that the capacity of the fluidreservoir is fixed and is defined by the internal surfaces of theexternal wall and the inner wall. Alternatively, a part of the innerwall of the reservoir, or a separate component which partially delimitsthe fluid reservoir, may be moveable relative to the external wall tovary the volume of the fluid reservoir. This moveable member may bemoved by a piston or other device which is actuated by the controlcircuit to reduce the volume of the fluid reservoir as working fluid issupplied to the fluid delivery system. This can inhibit the formation ofan air lock within the fluid reservoir as working fluid is supplied tothe fluid delivery system. The piston may be actuated by the controlcircuit simultaneously with the actuation of the pump to draw workingfluid from the fluid reservoir so that the reduction in the volume ofthe fluid reservoir is equal to the volume of working fluid which isdrawn from the fluid reservoir by the pump.

Alternatively, this moveable member may be moveable in response to apressure difference established across the surfaces thereof as workingfluid is supplied to the fluid delivery system. The appliance maycomprise an expansion chamber located adjacent to the moveable member,preferably to one side of the moveable member, and which increases involume as the volume of the fluid reservoir decreases as working fluidis supplied to the fluid delivery system.

In an eighth aspect, the present invention provides a dental cleaningappliance comprising a handle, a fluid reservoir for storing a workingfluid, the fluid reservoir being at least partially delimited by a wall,preferably an external wall, and a movable member which is moveablerelative to the wall to vary the volume of the fluid reservoir, a fluiddelivery system for receiving working fluid from the fluid reservoir,and for delivering the working fluid to the teeth of a user, and anexpansion chamber located adjacent to the moveable member and whichincreases in volume as the volume of the fluid reservoir decreases asworking fluid is supplied to the fluid delivery system.

The expansion chamber may contain a pressurized gas which exerts a forceon the moveable member which causes the moveable member to move asworking fluid is supplied to the fluid delivery system. However, theexpansion chamber is preferably open to the atmosphere to receiveambient air as the volume of the expansion chamber increases.

The external wall is preferably formed from relatively rigid material,and the moveable member is preferably formed from relatively flexiblematerial. In a preferred embodiment, the moveable member comprises adiaphragm or bladder which is expandable in response to a pressuredifference across the surfaces thereof.

The external wall preferably surrounds the diaphragm. The diaphragm ispreferably annular or tubular in shape, and preferably has opposite endswhich are connected to the external wall, preferably at diametricallyopposed locations on the external wall. The wall and the diaphragmpreferably extend about a common longitudinal axis so that as thediaphragm expands, the diaphragm expands outwardly away from thelongitudinal axis.

The diaphragm preferably extends about the expansion chamber so that arelatively uniform force is applied over the surface of the diaphragm topull the diaphragm towards the fluid reservoir as working fluid issupplied to the fluid delivery system. This can promote a uniformexpansion of the diaphragm as working fluid is supplied to the fluiddelivery system. To minimize the number of components of the appliance,preferably the diaphragm at least partially delimits the expansionchamber. For example, the diaphragm may be located between, and define abarrier between, the expansion chamber and the fluid reservoir. Theexpansion chamber is preferably annular in shape. The expansion chambermay be delimited by the diaphragm and the stem of the cleaning tool ofthe appliance. Alternatively, the expansion chamber may be delimited bythe diaphragm and a wall which defines a port through which air entersthe expansion chamber. The wall of the expansion chamber preferablyextends around, and is coaxial with, the stem. The wall of the expansionchamber is preferably connected to the external wall and the diaphragm,and is preferably moveable with the external wall as it is movedrelative to the stem. In other words, both the fluid reservoir and theexpansion chamber are preferably moveable, or rotatable, relative to thestem.

As the diaphragm expands, the size and shape of the diaphragm approachesthat of the external wall of the reservoir. In other words, when thediaphragm is in a fully expanded configuration, which occurs when thefluid reservoir is empty, the size and shape of the diaphragm arepreferably substantially the same as the external wall of the reservoir.When the diaphragm is in a fully contracted or deflated configuration,which occurs when the fluid reservoir has been filled to capacity, thesize and shape of the moveable member are preferably substantially thesame as the wall of the expansion chamber. Thus, the expansion chamberpreferably has a maximum volume which is substantially the same as themaximum volume of the fluid reservoir.

As mentioned above, the external wall of the fluid reservoir ispreferably transparent, which allows the user to see both the contentsof the fluid reservoir and, when the working fluid is water, thediaphragm. At least part of the diaphragm is preferably formed fromcolored material, or otherwise bears an identifier which serves todistinguish the cleaning tool of the appliance from others. This canallow a cleaning tool to bear an identifier which can serve todistinguish that cleaning tool from those of other users of theappliance, or to distinguish the appliance from other similarappliances. For example, the cleaning tool may form one of a set ofsimilar cleaning tools, where each cleaning tool within the set has arespective different such identifier.

In a ninth aspect, the present invention provides a dental cleaningappliance comprising a handle, a cleaning tool comprising a fluidreservoir for storing a working fluid, the fluid reservoir being atleast partially delimited by a transparent external wall and an innerwall, the inner wall bearing an identifier for user identification ofthe cleaning tool, and a fluid delivery system for receiving workingfluid from the fluid reservoir, and for delivering the working fluid tothe teeth of a user.

The identifier may be a color. For example, the inner wall may be formedfrom colored material. Alternatively, the identifier may comprise one ormore alphanumeric characters molded or otherwise formed on the innerwall. As mentioned above, the inner wall may be formed from relativelyflexible material, and may comprise a diaphragm which is movablerelative to the external wall.

The fluid delivery system preferably comprises a cleaning tool conduitsystem and a handle conduit system. The handle conduit system preferablycomprises a fluid inlet for receiving working fluid from the fluidreservoir, and a plurality of conduits for conveying working fluidbetween the fluid inlet, the pump, the accumulator, the solenoid valve,and a fluid outlet port. The cleaning tool conduit system preferablycomprises a fluid inlet port for receiving a burst of working fluid fromthe handle fluid outlet port, the flexible, or resilient fluid conduit,the pivotable fluid conduit, and the nozzle.

As mentioned above, the cleaning tool is preferably detachably connectedto the handle. As the cleaning tool is connected to the handle, thecleaning tool fluid inlet port aligns with the handle fluid outlet port.One of the fluid inlet port and the fluid outlet port may comprise afemale fluid connection, and the other one of the fluid inlet port andthe fluid outlet port may comprise a male fluid connection, or pipe,which protrudes from a body of the cleaning tool, and which is receivedby the female fluid connection as the cleaning tool is connected to thehandle.

To align the fluid inlet port with the fluid outlet port as the cleaningtool is connected to the handle, the handle preferably comprises anon-rotatable first connector, and the cleaning tool preferablycomprises a second connector for connecting with the first connector toconnect the handle to the cleaning tool. The first connector ispreferably a male connector extending parallel to a longitudinal axis ofthe handle, and the second connector is preferably a female connectorfor receiving the male connector. The male connector is preferably inthe form of a rod or spigot which protrudes from an external surface ofthe handle. Alternatively, the second connector may be in the form of amale connector, and the first connector may be in the form of a femaleconnector.

To facilitate alignment of the cleaning tool fluid inlet port with thehandle fluid outlet port, each of the male connector and the handlefluid outlet port is preferably radially spaced from the longitudinalaxis of the handle. To connect the cleaning tool to the handle, the uservisually aligns the cleaning tool longitudinally with the handle, androtates the cleaning tool relative to the handle, or vice versa, so thatthe male connector is aligned with the female connector. The maleconnector is then pushed into the female connector, and simultaneouslythe cleaning tool fluid inlet port aligns with, or enters, the handlefluid outlet port.

In a tenth aspect, the present invention provides a dental cleaningappliance comprising a cleaning tool, and a handle detachably connectedto the cleaning tool, the handle comprising a non-rotatable firstconnector, and a handle conduit system comprising a handle fluid outletport spaced from the first connector, each of the first connector andthe handle fluid outlet port being located on an end surface of thehandle and radially spaced from the longitudinal axis of the handle, thecleaning tool comprising a second connector for connecting with thefirst connector to connect the handle to the cleaning tool, and acleaning tool conduit system comprising a cleaning tool fluid inlet portwhich aligns with the handle fluid outlet port when the cleaning tool isconnected to the handle.

The cleaning tool preferably comprises a bristle carrier, a plurality ofbristles mounted on the bristle carrier, and a transmission unitconnected to the bristle carrier, and the handle preferably comprises adrive unit for driving the transmission unit to move the bristle carrierrelative to the handle. The handle preferably comprises a drive unitcoupling member for coupling with a transmission unit coupling memberlocated on the cleaning tool. The drive unit coupling member ispreferably spaced from each of the longitudinal axis of the handle, themale connector and the handle fluid outlet port. The handle fluid outletport is preferably angularly spaced from the drive unit coupling member.The handle fluid outlet port is preferably located diametricallyopposite to the drive unit coupling member. The male connector ispreferably located angularly between, more preferably angularly mid-waybetween, the handle fluid outlet port and the drive unit couplingmember.

The drive unit coupling member is preferably rotatable relative to thehandle. Preferably, the drive unit coupling member protrudes from a bodyof the handle, and is received by the transmission unit coupling memberas the cleaning tool is connected to the handle.

The male connector of the handle and the female connector of thecleaning tool preferably form a snap-fit connector for connecting thecleaning tool to the handle.

As discussed above, the appliance may comprise a control circuit foractuating the delivery of working fluid to the teeth of the userdepending on the output from a sensor. The sensor is preferably arrangedto detect movement of a part of the fluid delivery system relative tothe handle. To reduce the risk of undesired ejection of bursts ofworking fluid when the nozzle is not located within an interproximal gapof the user, for example during handling of the appliance, the appliancepreferably has a first operational mode in which the delivery of theburst of working fluid to the teeth of a user is inhibited and a secondoperational mode in which the burst of working fluid to the teeth of auser is permitted, and wherein, during use of the appliance, the controlcircuit is arranged to effect a transition between the first operationalmode and the second operational mode automatically depending on adetected operational parameter of the appliance.

In an eleventh aspect, the present invention provides a dental cleaningappliance comprising a fluid delivery system for delivering a burst ofworking fluid to the teeth of a user, and a control circuit forcontrolling the delivery of the burst of working fluid to the teeth of auser, wherein the appliance has a first operational mode in which thedelivery of the burst of working fluid to the teeth of a user isinhibited and a second operational mode in which the burst of workingfluid to the teeth of a user is permitted, and wherein, during use ofthe appliance, the control circuit is arranged to effect a transitionbetween the first operational mode and the second operational modeautomatically depending on a detected operational parameter of theappliance.

One of a number of different operational parameters of the appliance maybe detected to effect a transition between the operational modes of theappliance. For example, the operational parameter may be one of:

-   -   the activation state (on or off) of the motor for driving the        rotation of the bristle carrier;    -   the magnitude of the current drawn by the motor;    -   the magnitude of a load applied to the appliance during use,        such as a force applied to the cleaning tool via the engaging        means, a force applied to the nozzle, or a force applied to the        handle as it is gripped by the user;    -   the orientation of the appliance;    -   the volume of working fluid in the accumulator; and    -   the position of the collar relative to the handle.

The control circuit is preferably arranged to effect a transitionbetween the first operational mode and the second operational mode whenthe detected operational parameter of the appliance is above a non-zerothreshold value.

In addition, or an alternative, to the delivery of a burst of workingfluid to the nozzle depending on the output from a sensor, the controlcircuit may be arranged to actuate the delivery of fluid to the teeth ofa user in response to a user action on the appliance. That user actionon the appliance may be the actuation of a button of the appliance.

For example, the appliance may have an “automatic” mode, or first modeof fluid delivery, which is selectable by the user and in which a burstof working fluid is delivered to the teeth of a user depending on theoutput from the sensor. When that mode is not selected by the user, orwhen a “manual” mode, or a second mode of delivery, is selected by theuser, the burst of working fluid is delivered to the user's teethdepending on the user action on the appliance.

Where the cleaning tool comprises a moveable bristle carrier, thedetected operational parameter preferably comprises the magnitude of thecurrent drawn by the motor to move the bristle carrier. The drive unitand the transmission unit are preferably arranged to generate a constantspeed of movement of the bristle carrier relative to the handle. Whenthe appliance is first activated, or switched on, by the user, theappliance tends not to be in contact with the user's teeth. As a result,the current drawn by the motor tends to be relatively low, and ispreferably below a set threshold value so that the appliance is in thefirst operational mode when first activated.

When the bristles are urged against the teeth of the user, theresistance to the motion of the bristle carrier increases depending onthe force with which the bristles are pressed against the teeth. Tomaintain a constant speed of movement of the bristle carrier, the motordraws an increased amount of current depending on the force applied tothe bristle carrier. The control circuit detects the magnitude of thecurrent drawn by the motor, and when that current exceeds a thresholdvalue, which is indicative of the current required to move the bristlesagainst a user's teeth, the control circuit effects the transition tothe second operational mode. When the detected current falls below thatthreshold value, the control circuit effects a transition back to thefirst operational mode.

As mentioned above, the nozzle is preferably moveable between a proximalposition and a distal position. In the distal position, the tip of thenozzle is preferably proud of at least some of the free ends of thebristles. As the bristles are pressed against a user's teeth, thebristles will deflect, reducing the direct spacing between the ends ofthe bristles and the bristle carrier and, simultaneously, moving the tipof the nozzle towards the bristle carrier, and so towards its proximalposition. Depending on how far the bristles bend during use, and thus onthe stiffness of the bristles, the movement of the nozzle relative tothe head can be detected from the variation of the output received fromthe sensor, and used as an indicator of the load being applied to thehead during use of the appliance. This can be particularly useful whenthe bristles are mounted on a static bristle carrier, or directly to thehead of the appliance.

In a twelfth aspect, the present invention provides a dental cleaningappliance comprising a handle, a cleaning tool connected to the handle,part of the cleaning tool being moveable relative to the handle as thecleaning tool is moved along a user's teeth, said part of the cleaningtool being moveable about a first axis, an arm having a first end whichis connected to said part of the cleaning tool for movement therewith,and a second end which is remote from the first end, the arm beingpivotably moveable relative to said part of the cleaning tool about asecond axis which is spaced from the first axis, and a sensor forgenerating an output which varies depending on the relative positions ofthe sensor and the second end of the arm.

As mentioned above, the cleaning tool is preferably detachably connectedto the handle. This can allow a handle to be provided with a set ofsimilar cleaning tools, each with a respective different identifier.This can also allow a handle to be provided with a set of dissimilarcleaning tools. For example, the set of cleaning tools may be selectedfrom two or more of a first type of cleaning tool with a nozzle and amoveable brush unit, a second type of cleaning tool with a nozzle and astatic brush unit, a third type of cleaning tool with a nozzle and nobristles, and a fourth type of cleaning tool with a moveable brush unitand no nozzle. A number of respective different cleaning tools of thesame type may also be provided, for example, of the first type ofcleaning tool, with bristles having a respective different stiffness, orwith nozzles having respective different fluid outlet sizes.

The appliance is preferably a handheld appliance which includes all ofthe aforementioned components of the appliance.

The cleaning tools may be sold as stand-alone items, for example asspare parts or as alternative cleaning tools for use with an existinghandle.

In a thirteenth aspect, the present invention provides a cleaning toolfor a dental cleaning appliance comprising a handle to which thecleaning tool is detachably connectable, the cleaning tool comprising astem, and a cleaning tool conduit system comprising a nozzle fordelivering a burst of working fluid to the teeth of a user, and amoveable fluid conduit which is moveable relative to the stem, thenozzle being moveable with the fluid conduit, the fluid conduit beingbiased for movement in a direction which urges the nozzle against auser's teeth during use of the appliance.

In a fourteenth aspect, the present invention provides a cleaning toolfor a dental cleaning appliance comprising a handle to which thecleaning tool is detachably connectable, the handle comprising a driveunit, the drive unit comprising a motor and a drive unit couplingmember, the cleaning tool comprising a cleaning tool fluid conduitsystem comprising a nozzle for delivering a burst of working fluid tothe teeth of a user, a brush unit comprising a bristle carrier and aplurality of bristles mounted on the bristle carrier, the brush unitextending about the nozzle, and a transmission unit connected to thebristle carrier for moving the bristle carrier relative to the nozzle,the transmission unit comprising a transmission unit coupling member forcoupling with the drive unit transmission unit when the cleaning tool isconnected to the handle.

In a fifteenth aspect, the present invention provides a cleaning toolfor a dental cleaning appliance comprising a handle to which thecleaning tool is detachably connectable, the cleaning tool comprising astem, a nozzle for delivering the burst of working fluid to the teeth ofa user, and a fluid reservoir for storing working fluid, the fluidreservoir being connected to and extending around the stem.

In a sixteenth aspect, the present invention provides a cleaning toolfor a dental cleaning appliance comprising a handle to which thecleaning tool is detachably connectable, the cleaning tool comprising astem, a fluid reservoir for storing a working fluid, and an externalcollar comprising a fluid port, the collar being moveable relative tothe stem between a first position in which, when the cleaning tool isconnected to the handle, the fluid port is exposed to allow the fluidreservoir to be replenished, and a second position in which, when thecleaning tool is connected to the handle, the fluid port is occluded.

In a seventeenth aspect, the present invention provides a cleaning toolfor a dental cleaning appliance comprising a handle to which thecleaning tool is detachably connectable, the handle comprising a handleconduit system, the cleaning tool comprising a fluid reservoir forsupplying a working fluid to the handle conduit system, the fluidreservoir being at least partially delimited by a wall and a movablemember which is moveable relative to the wall to vary the volume of thefluid reservoir, a cleaning tool conduit system for receiving a burst ofworking fluid from the handle conduit system and for delivering theburst of working fluid to the teeth of a user, and an expansion chamberlocated adjacent to the moveable member and which increases in volume asthe volume of the fluid reservoir decreases as working fluid is suppliedto the handle conduit system.

The handle of the appliance may also be provided separately from thecleaning tool, for example as a spare part for the appliance, or for useby a different user. For example, handles having respective differentshapes may be provided for use by users of different age.

In an eighteenth aspect, the present invention provides a handle for adental cleaning appliance comprising a cleaning tool to which the handleis detachably connectable, the cleaning tool comprising a nozzle throughwhich a burst of working fluid is delivered to the teeth of a user, thehandle comprising a fluid inlet, a pump for drawing working fluidthrough the fluid inlet, a hydraulic accumulator for receiving workingfluid from the pump, a fluid outlet which is in fluid communication withthe nozzle when the cleaning tool is connected to the handle, a valvelocated between the accumulator and the fluid outlet, the valve havingan open position for enabling the accumulator to deliver a burst ofworking fluid to the fluid outlet and a closed position for enabling theaccumulator to be replenished under the action of the pump, and acontrol circuit for controlling the position of the valve.

In a nineteenth aspect, the present invention provides a handle for adental cleaning appliance comprising a cleaning tool to which the handleis detachably connectable, the cleaning tool comprising a fluidreservoir for storing a working fluid, and a moveable collar having afluid port in fluid communication with the fluid reservoir, the handlecomprising a body comprising a recessed portion for exposing the fluidport when the cleaning tool is connected to the handle and the collar isin a first position relative to the body, and a handle conduit systemcomprising a fluid inlet for receiving working fluid from the fluidreservoir when the cleaning tool is connected to the handle and thecollar is in a second position relative to the body.

One or more of the aforementioned aspects of the invention may also beapplied more generally to cleaning apparatus or a cleaning appliance.The apparatus may be a surface treating appliance. For example, theapparatus may be in the form of apparatus, preferably a handheldapparatus, for cleaning a work surface, in which the brush unit isarranged to engage a work surface and the nozzle is arranged to delivercleaning fluid to the work surface during cleaning.

In a twentieth aspect, the present invention provides a surface treatingappliance comprising a handle, a fluid delivery system comprising anozzle for delivering a burst of working fluid to a surface, a brushunit for engaging the surface, the brush unit comprising a bristlecarrier and a plurality of bristles mounted on the bristle carrier, thebrush unit extending at least partially about the nozzle, and a driveunit for driving movement of the bristle carrier relative to the nozzle.

In a twenty first aspect, the present invention provides a surfacetreating appliance comprising a fluid delivery system comprising a fluidinlet, a pump for drawing a working fluid through the fluid inlet, ahydraulic accumulator for receiving working fluid from the pump, anozzle having a fluid outlet, and a valve located between theaccumulator and the nozzle, the valve having an open position forenabling the accumulator to deliver a burst of working fluid to thenozzle and a closed position for enabling the accumulator to bereplenished under the action of the pump, and a control circuit foractuating the pump, and for controlling the position of the valve.

In a twenty second aspect, the present invention provides a surfacetreating appliance comprising a handle and a cleaning tool detachablyconnected to the handle, the cleaning tool comprising a nozzle fordelivering a burst of working fluid to a surface, a stem extendingbetween the handle and the nozzle, and a fluid reservoir for storingworking fluid, the fluid reservoir being connected to and extendingaround the stem.

In a twenty third aspect, the present invention provides a surfacetreating appliance comprising a handle, a fluid reservoir for storing aworking fluid, a fluid delivery system for receiving working fluid fromthe fluid reservoir, and for delivering a burst of working fluid to asurface, and an external collar comprising a fluid port, the collarbeing moveable relative to the handle between a first position in whichthe fluid port is exposed to allow the fluid reservoir to bereplenished, and a second position in which the fluid port is occluded.

In a twenty fourth aspect, the present invention provides a surfacetreating appliance comprising a handle, a fluid reservoir for storing aworking fluid, the fluid reservoir being at least partially delimited bya wall and a movable member which is moveable relative to the wall tovary the volume of the fluid reservoir, a fluid delivery system forreceiving working fluid from the fluid reservoir, and for delivering theworking fluid to a surface, and an expansion chamber located adjacent tothe moveable member and which increases in volume as the volume of thefluid reservoir decreases as working fluid is supplied to the fluiddelivery system.

Features described above in connection with the first aspect of theinvention are equally applicable to each of the second to twenty fourthaspects of the invention, and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention will now be described by wayof example only with reference to the accompanying drawings, in which:

FIG. 1(a) is a right side view of a dental cleaning appliance, FIG. 1(b)is a front view of the appliance, and FIG. 1(c) is a left side view ofthe appliance;

FIG. 2(a) is a left side perspective view, for above, of the appliance,and FIG. 2(b) is a right side perspective view, from above, of theappliance;

FIG. 3 is a right side perspective view, from above, of a cleaning toolof the appliance;

FIG. 4 is a right side perspective view, from above, of a handle of theappliance;

FIG. 5 is a perspective view of a drive mechanism for driving themovement of a brush unit relative to the handle;

FIG. 6 is a cutaway view of part of the handle;

FIGS. 7(a) to 7(d) is a series of views which illustrate the movement ofthe brush unit, and a transmission unit of the drive mechanism, relativeto the handle;

FIG. 8(a) is a top view of the head of the cleaning tool, and FIG. 8(b)is a sectional view of the head taken along line A-A in FIG. 8(a);

FIG. 9 illustrates schematically components of a fluid delivery systemfor delivering a burst of a working fluid to the teeth of a user, and acontrol system for controlling the fluid delivery system;

FIG. 10 is a similar view to FIG. 2(a), but with the outer body of thehandle removed;

FIG. 11(a) is a similar view to FIG. 2(b), but with the outer body ofthe handle removed and with a collar of the cleaning tool in a firstposition relative to the handle, and FIG. 11(b) is a similar view toFIG. 11(a), but with the collar in a second position relative to thehandle;

FIG. 12(a) is a sectional view of a fluid reservoir of the cleaningtool, and with a diaphragm of the fluid reservoir in a fully contractedconfiguration, FIG. 12(b) is a similar view to FIG. 12(a) but with thediaphragm in a partially expanded configuration, and FIG. 12(c) is asimilar view to FIG. 12(a) but with the diaphragm in an almost fullyexpanded configuration;

FIGS. 13(a) and 13(b) are sectional view of a diaphragm pump of thefluid delivery system, with the pump in intake and output configurationsrespectively;

FIGS. 14(a) and 14(b) are sectional views of a spring-type accumulatorof the fluid delivery system, with a fluid chamber of the accumulator inempty and full configurations respectively;

FIGS. 15(a) and 15(b) are sectional views of an alternative gas-chargedaccumulator of the fluid delivery system, with a fluid chamber of theaccumulator in empty and full configurations respectively;

FIG. 16(a) is a sectional view of a solenoid valve of the fluid deliverysystem, and FIG. 16(b) is an exploded sectional view of the solenoidvalve;

FIG. 17(a) is a front view of the cleaning tool and interfacingcomponents of the body of the handle, FIG. 17(b) is a right side view ofthe cleaning tool and interfacing components of the body of the handle,and FIG. 17(c) is a side sectional view taken along line E-E in FIG.17(a);

FIG. 18(a) is a perspective view of a cleaning tool conduit system, FIG.18(b) is a similar view to FIG. 18(a) but with the addition of apivotable support for a fluid conduit of the cleaning tool conduitsystem, FIG. 18(c) is a similar view to FIG. 18(b) but with the additionof a static guide member, and FIG. 18(d) is a similar view to FIG. 18(b)but with the addition of the transmission unit, part of the brush unitand a system for detecting motion of the support;

FIG. 19(a) is a side view of the assembly of FIG. 18(d) with the nozzlein a distal position relative to the cleaning tool, and FIG. 19(b) is asimilar view to FIG. 19(a) with the nozzle in a proximal positionrelative to the cleaning tool;

FIG. 20 illustrates the replenishment of the fluid reservoir withworking fluid; and

FIGS. 21(a) to (f) illustrate schematically the movement of the cleaningtool over a user's teeth and the ejection of working fluid into aninterproximal gap.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 illustrate external views of an embodiment of a dentalcleaning appliance 10. In this embodiment, the appliance is in the formof a handheld appliance, which is in the form of an electric toothbrushhaving an integrated assembly for dispensing a working fluid forimproved interproximal cleaning.

The appliance 10 comprises a handle 12 and a cleaning tool 14. Thehandle 12 comprises an external body 16 which is gripped by a userduring use of the appliance 10. The body 16 is preferably formed fromplastics material, and is preferably generally cylindrical in shape. Thehandle 12 comprises a plurality of user operable buttons 18, 20, 22which are located within respective apertures formed in the body 16 soas to be accessible to the user. The handle 12 further comprises adisplay 24 which is positioned so as to be visible to a user during useof the appliance. In this embodiment, the display 24 is also locatedwithin a respective aperture formed in the body 16.

The cleaning tool 14 comprises a stem 26 and a head 28. The stem 26 iselongate in shape, which serves to space the head 28 from the handle 12to facilitate user operability of the appliance 10. The head 28comprises a brush unit 29, which comprises a bristle carrier 30 and aplurality of bristles 32 mounted on the bristle carrier 30. As discussedin more detail below, the bristle carrier 30 is moveable relative to thestem 26 and the handle 12. The cleaning tool 14 also comprises a fluidreservoir 34 for storing a working fluid, and a nozzle 36 for deliveringone or more bursts of working fluid to the teeth of the user during useof the appliance 10. The fluid reservoir 34 is connected to the stem 26.The fluid reservoir 34 extends at least partially around the stem 26.The brush unit 29 extends at least partially around the nozzle 36. Thefluid reservoir 34 and the nozzle 36 are also discussed in more detailbelow.

The cleaning tool 14 is detachably connected to the handle 12. Withreference to FIGS. 3 and 4, the handle 12 comprises a male connector 38,preferably in the form of a pin or spigot, which is received by acomplementary female connector 40, preferably in the form of a recess,of the cleaning tool 14. The male connector 38 preferably protrudesoutwardly from a concave end surface 42 of the body 16, and preferablyin a direction which is parallel to the longitudinal axis X of thehandle 12. The end surface 42 defines a recess for receiving a convexend surface of the cleaning tool 14 so that, as illustrated in FIGS. 1to 3, part of the outer surface of the cleaning tool 14 is occluded orcovered by the handle 12 when the cleaning tool 14 is connected to thehandle 12.

The male connector 38 is radially spaced from the longitudinal axis X ofthe handle 12, and the female connector 40 is similarly spaced from thelongitudinal axis Y of the cleaning tool 14. To connect the cleaningtool 14 to the handle 12, the user visually aligns the longitudinal axisX of the handle 12 with the longitudinal axis Y of the cleaning tool 14,and angularly aligns the connectors 38, 40 before pushing the cleaningtool 14 towards the handle 12 to insert the male connector 38 into thefemale connector 40. The connectors 38, 40 preferably form a snap-fitconnection when the male connector 38 has been inserted fully into thefemale connector 40. The connectors 38, 40 may be subsequentlydisconnected by pulling apart the handle 12 and the cleaning tool 14.

As mentioned above, the cleaning tool 14 includes a bristle carrier 30which is moveable relative to the stem 26. With reference also to FIGS.5 to 8, the appliance 10 comprises a drive mechanism 50 for driving themovement of the bristle carrier 30 relative to the stem 26. The drivemechanism 50 comprises a transmission unit 52 connected to the bristlecarrier 30, and a drive unit 54 for driving the transmission unit 52 tomove the bristle carrier 30 relative to the stem 26.

The handle 12 comprises the drive unit 54 of the drive mechanism 50. Thedrive unit 54 comprises a motor 56, preferably in the form of a dcmotor, which is actuated by a control circuit 58 (shown in FIG. 10) inresponse to the user depression of one or more of the buttons of thehandle 12, as described below. The motor 56 is powered by a battery 60(also shown in FIG. 10) located within the handle 12. The battery 60 maybe a non-rechargeable battery which may be accessed for replacement bythe user via a removable cover 62 located in the base of the handle 12.Alternatively, the battery 60 may be a rechargeable battery, which maybe charged as required by the user using a wireless battery charger, asis known.

The motor 56 is connected to a gear train located within the handle 12.The gear train comprises a first spur gear 64 connected to a rotaryshaft of the motor 56, and a second spur gear 66 which meshes with thefirst spur gear 64 and is supported by a shaft 68 for rotation about anaxis which is generally parallel with the rotational axis of the motor56. The second spur gear 66 is connected to a drive unit coupling member70 which protrudes outwardly from the end surface 42 of the body 16, andwhich rotates relative to the body 16 upon actuation of the motor 56.The drive unit coupling member 70 is also spaced from the longitudinalaxis X of the handle 12, and is preferably angularly spaced from themale connector 38.

The cleaning tool 14 comprises the transmission unit 52 of the drivemechanism 50. The transmission unit 52 comprises a transmission unitcoupling member 72 which couples with, and preferably receives, thedrive unit coupling member 70 when the cleaning tool 14 is connected tothe handle 12. The transmission unit coupling member 72 is connected toa gear train located in the cleaning tool 14. The gear train comprises afirst contrate gear 74 which is connected to the transmission unitcoupling member 72, and a second contrate gear 76 which meshes at aright angle with the first contrate gear 74 so that the second contrategear 76 rotates about an axis which is orthogonal to the longitudinalaxis Y of the cleaning tool 14.

A crank 78 is connected to the second contrate gear 76 such that theaxis of the crank 78 is spaced from the rotational axis of the secondcontrate gear 76. With rotation of the second contrate gear 76, thecrank 78 moves in a circular orbital path centred on the rotational axisof the second contrate gear 76. A first end 80 of an elongate connectingrod 82 is connected to the crank 78 for movement with the crank 78 aboutthe rotational axis of the second contrate gear 76. The connecting rod82 is housed within the stem 26. The other end of the connecting rod 82is connected to the side surface of the bristle carrier 30. Lateralmovement of the connecting rod 82 relative to the stem 26 is constrainedby a pair of parallel guide members 84, 86 connected to the stem 26, andwhich each engage a respective side surface of the connecting rod 82,and so that orbital movement of the crank 78 results in orbital movementof the bristle carrier 30 about a circular orbital path relative to thestem 26.

As mentioned above, the brush unit 29, which comprises the bristlecarrier 30 and the bristles 32, extends at least partially around thenozzle 36. In this embodiment, the bristle carrier 30 surrounds thenozzle 36. As shown in FIGS. 7 and 8, the bristle carrier 30 is annularin shape, and is preferably spaced from the nozzle 36 so that thebristle carrier 30 moves relative to the nozzle 36. The orbital path ofthe bristle carrier 30 is preferably generally centred on the nozzle 36.The radius of the orbital path is preferably in the range from 0.5 to 1mm.

The nozzle 36 forms part of a fluid delivery system 100 for receivingworking fluid from the fluid reservoir 34 and for delivering bursts ofworking fluid to the teeth of a user during use of the appliance 10. Thetip of the nozzle 36 comprises a fluid outlet 102 through which a burstof working fluid is delivered to the teeth of the user. The fluiddelivery system 100 is illustrated schematically in FIG. 9. In overview,the fluid delivery system 100 comprises a fluid inlet 104 for receivingworking fluid from the fluid reservoir 34. In this embodiment, theworking fluid is a liquid working fluid, which is preferably water. Thefluid delivery system 100 comprises a pump 106 for drawing working fluidfrom the fluid reservoir 34 through the fluid inlet 104, and fordelivering the working fluid to a hydraulic accumulator 108. A firstone-way valve 110 is located between the fluid inlet 104 and the pump106, and a second one-way valve 112 is located between the pump 106 andthe accumulator 108. A solenoid valve 114 is located downstream from theaccumulator 108. The control circuit 58 controls the movement of thesolenoid valve 114 between a closed position, which is adopted whenworking fluid is being delivered to the accumulator 108 by the pump 106,and an open position, which is adopted to effect the delivery of a burstof working fluid from the accumulator 108 to the nozzle 36.

The fluid inlet 104, the pump 106, the accumulator 108 and the solenoidvalve 114 are located in the handle 12. In other words, a first part ofthe fluid delivery system 100 is located in the handle 12, and a secondpart of the fluid delivery system 100 is located in the cleaning tool14. The fluid delivery system 100 thus comprises a handle conduit system116 which is located in the handle 12, and a cleaning tool conduitsystem 118 which is located in the cleaning tool 14. With reference alsoto FIGS. 3 and 4, the fluid inlet 104 provides a fluid inlet of thehandle conduit system 116, and a handle fluid outlet port 120 provides afluid outlet of the handle conduit system 116.

The fluid reservoir 34 is connected to, and extends at least partiallyaround, the stem 26 of the cleaning tool 14. In this embodiment, thefluid reservoir 34 is annular in shape, and so surrounds the stem 26.The fluid reservoir 34 is preferably located at or towards the end ofthe stem 26 which is remote from the head 28. The fluid reservoir 34preferably has a capacity in the range from 5 to 50 ml, and in thisembodiment has a capacity of 25 ml.

The fluid inlet 104 is arranged to receive working fluid from the fluidreservoir 34, and so in this embodiment the fluid inlet 104 is locatedon the concave end surface 42 of the body 16 of the handle 12. Withreference to FIGS. 10 to 12(c), working fluid is supplied to the fluidinlet 104 of the handle conduit system 116 from a fluid port 122 whichis in fluid communication with the fluid reservoir 34. The fluid port122 is located on an external collar 124 of the cleaning tool 14. Thecollar 124 is moveable relative to both the handle 12 and the stem 26 ofthe cleaning tool 14. In this embodiment, the collar 124 is rotatablerelative to the handle 12 about the longitudinal axis Y of the cleaningtool 14. To move the collar 124 relative to the handle 12, the usergrasps the handle 12 with one hand, and, with the other hand, turns thecollar 124 about the longitudinal axis Y in the desired angulardirection.

The collar 124 is moveable relative to the handle 12 between a firstposition, as illustrated in FIG. 11(a), and a second position, asillustrated in FIG. 11(b). The second position is angularly spaced fromthe first position, preferably by an angle in the range from 60 to 180°,and in this embodiment by an angle of around 90°.

When the collar 124 is in the first position relative to the handle 12,as also illustrated in FIGS. 1 to 3 and 10, the fluid port 122 isexposed to allow the fluid reservoir 34 to be replenished by the user.The fluid port 122 is exposed by a recessed portion 126 of the body 16of the handle 12. The recessed portion 126 comprises a curved wall 128.The curved wall 128 is shaped so that, during filling or replenishmentof the fluid reservoir 34 by the user, working fluid is guided towardsthe exposed fluid port 122.

When the collar 124 is in the second position relative to the handle 12,the fluid port 122 is occluded by the handle 12 so that the fluid port122 is not accessible by the user. As the fluid port 122 also serves tosupply working fluid to the handle conduit system 116, in the secondposition the fluid port 122 is placed in fluid communication with thefluid inlet 104. The end surface 42 of the body 16 comprises an annularseal, or O-ring, 130 which extends about the fluid inlet 104. When thecollar 124 is in the second position, the seal 130 engages an annularportion of the surface of the collar 124 which surrounds the fluid port122 to inhibit leakage of working fluid from the fluid reservoir 34. Oneor more stop members may be provided on one, or both, of the fluidreservoir 34 and the handle 12 to inhibit the movement of the collar 124beyond the first position and the second position.

The collar 124 may be spaced from the fluid reservoir 34, but in thisembodiment the collar 124 forms part of an external wall 132 of thefluid reservoir 34. The external wall 132 of the fluid reservoir 34 isthus moveable relative to the handle 12 and the stem 26 of the cleaningtool 14. The external wall 132 is preferably transparent to allow a userto observe the contents of the fluid reservoir 34, and so assess whetherthe fluid reservoir 34 requires replenishment prior to the desired useof the appliance 10.

The external wall 132 of the fluid reservoir 34 extends around the stem26 of the cleaning tool 14. The external wall 132 preferably has a shapewhich is symmetrical about the longitudinal axis Y of the cleaning tool14. The external wall 132 preferably has a curved shape, more preferablya convex curved shape, but alternatively the external wall 132 may havea polygonal or faceted shape. In this embodiment, the external wall 132has a spherical curvature. The external wall 132 has diametricallyopposed circular apertures 134, 136 which are centred on thelongitudinal axis Y of the cleaning tool 14 to allow the stem 26 of thecleaning tool 14 to pass therethrough.

The fluid reservoir 34 further comprises an inner wall 138 which isconnected to the external wall 132. The external wall 132 and the innerwall 138 together define the capacity of the fluid reservoir 34. Theinner wall 138 is tubular in shape, and also surrounds the stem 26 ofthe cleaning tool 14. The ends 140, 142 of the inner wall 138 arepreferably circular in shape, and are connected to the external wall 132so as to form a fluid-tight seal between the external wall 132 and theinner wall 138.

The inner wall 138 thus moves with the external wall 132 as the collar124, which in this embodiment forms part of the external wall 132, movesrelative to the handle 12. The entire fluid reservoir 34 may beconsidered to be moveable relative to the handle 12 as the collar 124 ismoved between its first and second positions relative to the handle 12.

The inner wall 138 has an external surface 144 which faces the externalwall 132 of the fluid reservoir 34. As the inner wall 138 is visible tothe user through the external wall 132, the external surface 144 of theinner wall 138 may bear an identifier for user identification of thecleaning tool 14. For example, the identifier may be a coloured portionof the external surface 144 of the inner wall 138, or one or morealphanumeric characters moulded or otherwise formed on the externalsurface 144 of the inner wall 138.

FIG. 12(a) illustrates the fluid reservoir 34 when it has been filledwith working fluid. In this embodiment, the external wall 132 is formedfrom relatively rigid material, and the inner wall 138 is formed fromrelatively flexible material. The thickness of the inner wall 138, andthe material from which the inner wall 138 is formed, are selected sothat at least part of the inner wall 138 is moveable relative to theexternal wall 132 in response to a pressure differential which isestablished across the inner wall 138 as working fluid is drawn from thefluid reservoir 34 by the pump 106. In this embodiment, the inner wall138 is in the form of a diaphragm or bladder which has ends 140, 142secured to the external wall 132, and which is expandable in response toa pressure differential which is generated across the surfaces 144, 146of the inner wall 138 as working fluid is drawn from the fluid reservoir34. FIG. 12(a) illustrates the inner wall 138 in a fully contractedconfiguration, or state, in which the capacity of the fluid reservoir 34is maximised.

In this embodiment, the cleaning tool 14 comprises an expansion chamber148 which is located adjacent to the inner wall 138. The expansionchamber 148 has a volume which increases as the volume of the fluidreservoir 34 decreases. In this embodiment, the expansion chamber 148 isopen to the atmosphere to allow atmospheric air to enter the expansionchamber 148 as the inner wall 138 moves towards the external wall 132 asworking fluid is supplied to the fluid delivery system 100. Theexpansion chamber 148 is shown in FIGS. 12(b) and 12(c), whichillustrate the inner wall 138 in a partially expanded configuration, andin an almost fully expanded configuration, respectively. The expansionchamber 148 is delimited by the internal surface 146 of the inner wall138, and the external surface 150 of an expansion chamber wall 152. Theexpansion chamber wall 152 is also generally tubular in shape, and isformed from relatively rigid material. The ends of the expansion chamberwall 152 are also connected to the ends of the external wall 132 and theinner wall 138 of the fluid reservoir 34 so that the expansion chamberwall 152 moves with the fluid reservoir 34 as the collar 124 is movedrelative to the handle 12. The expansion chamber wall 152 is preferablyin the form of a sleeve which extends around, and is moveable relativeto, the outer wall of the stem 26. One or more apertures or ports 154are formed in the expansion chamber wall 152 to allow atmospheric air toenter the expansion chamber 148, for example, from an air flow pathwhich extends between the stem 26 and the expansion chamber wall 152,with expansion of the inner wall 138.

As the inner wall 138 expands towards its fully expanded configuration,the size and shape of the inner wall 138 approaches that of the externalwall 132. In other words, when the inner wall is in a fully expandedconfiguration, which occurs when the fluid reservoir 34 is substantiallyempty, the size and the shape of the inner wall 138 are substantiallythe same as the size and the shape of the external wall 132 of the fluidreservoir 34. Thus, the maximum volume of the expansion chamber 148 ispreferably substantially the same as the maximum volume of the fluidreservoir 34.

Working fluid is drawn from the fluid reservoir 34 by a pump 106 of thefluid delivery system 100. The pump 106 is fluidly connected to thefluid inlet 104 by a fluid conduit 156 of the handle fluid conduitsystem 116. The pump 106 is preferably in the form of a diaphragm pump,which incorporates the one-way valves 110, 112 of the fluid deliverysystem 100. With reference to FIGS. 13(a) and 13(b), the pump 106comprises a motor 160 which is actuated by the control circuit 58. Themotor 160 is also powered by the battery 60. The motor 160 drives a geartrain 162 which is connected to the centre of a diaphragm 164 by a crank166. The diaphragm 164 delimits a pump chamber 168 having a chamberinlet 170 and a chamber outlet 172. During activation of the motor 160,the diaphragm 164 moves between a first configuration, as shown in FIG.13(a), and a second configuration, as shown in FIG. 13(b). As thediaphragm 164 moves towards the first configuration, the first one-wayvalve 110 is pulled into an open position, and the second one-way valve112 is pulled into a closed position, as shown in FIG. 13(a). Thisallows working fluid to be drawn into the expanding pump chamber 166through the chamber inlet 170. With subsequent movement of the diaphragm164 towards the second configuration, the first one-way valve 110 ispushed into a closed position, and the second one-way valve 112 ispushed into an open position, as shown in FIG. 13(b). This allowsworking fluid to be pushed from the contracting pump chamber 166 throughthe chamber outlet 172.

With the second one-way valve 110 in an open position and the solenoidvalve 114 in a closed position, working fluid is conveyed by fluidconduit 174 to the accumulator 108. A first embodiment of an accumulator108 is illustrated in FIGS. 14(a) and 14(b), in which the accumulator108 is in the form of a spring-type accumulator. The accumulator 108comprises a fluid port 180 for receiving working fluid from the fluidconduit 174, and for conveying the received working fluid to a fluidchamber 182. The fluid chamber 182 is delimited by an elastic diaphragm184 which is urged by a spring-loaded piston 186 towards the fluid port180, and thus in a direction which urges working fluid from the fluidchamber 182 back through the fluid port 180. As working fluid enters thefluid chamber 182 from the pump 106, the diaphragm is urged, by theworking fluid within the fluid chamber 182, away from the fluid port180, as shown in FIG. 14(b), against the biasing force of the spring188. A stop member may be provided for restricting the movement of thepiston 186 away from the fluid port 180. The stop member may comprise asensor which generates an output to the control circuit 58 upon contactwith the piston 186. When the second one-way valve 112 is in a closedposition, and with the solenoid valve 114 remaining in the closedposition, a volume of working fluid is held under pressure within thefluid chamber 182.

An alternative, second embodiment of an accumulator 190 is illustratedin FIGS. 15(a) and 15(b), in which the accumulator 190 is in the form ofa gas-charged accumulator. Similar to the accumulator 108, theaccumulator 190 comprises a fluid port 192 for receiving working fluidfrom the fluid conduit 174, and for conveying the received working fluidto a fluid chamber 194. The fluid chamber 194 is delimited by an elasticdiaphragm 196 which is urged by a gas-filled chamber 198 towards thefluid port 192, and thus in a direction which urges working fluid fromthe fluid chamber 194 back through the fluid port 192. As working fluidenters the fluid chamber 194 from the pump 106, the diaphragm is urged,by the working fluid within the fluid chamber 182, away from the fluidport 180, as shown in FIG. 15(b), against the biasing force exerted onthe diaphragm 196 by the gas within the gas-filled chamber 198. When thesecond one-way valve 112 is in a closed position, and with the solenoidvalve 114 remaining in the closed position, a volume of working fluid isheld under pressure within the fluid chamber 194. Again, a stop membermay be provided for restricting the movement of the diaphragm 196 awayfrom the fluid port 192. The stop member may comprise a sensor whichgenerates an output to the control circuit 58 upon contact with thediaphragm 196.

A sectional view of the solenoid valve 114 is illustrated in FIG. 16(a),and in exploded form in FIG. 16(b). The solenoid valve 114 comprises acore housing 200, which comprises a fluid inlet 202 of the solenoidvalve 114, and a lower valve housing 204 which comprises a fluid outlet206 of the solenoid valve 114. An O-ring 208 forms a seal between thecore housing 200 and the lower valve housing 204. The lower valvehousing 204 defines a valve seat 210 against which a core 212 is urgedby a spring 214 located between the core housing 200 and the core 212. Acoil 216 is located around the core housing 200, and a flux conductor218 is located around the coil 216. The coil 216 is connected to thecontrol circuit 58, which selectively energizes the coil 216 to generatea magnetic field which pulls the core 212 away from the valve seat 210,and so actuate a transition of the solenoid valve 114 from a closedposition, as illustrated in FIG. 16(a), to an open position to allowworking fluid to pass from the fluid inlet 202 to the fluid outlet 206.When the coil 216 is de-energised, the spring 214 urges the core 212against the valve seat 210 to place the solenoid valve 214 in a closedposition.

The fluid outlet 206 of the solenoid valve 114 is connected to thehandle fluid outlet port 120 by fluid conduit 222. As illustrated inFIG. 4, the handle fluid outlet port 120 is located adjacent to thefluid inlet 104 on the end surface 42 of the body 16. The handle fluidoutlet port 120 is also spaced from the longitudinal axis X of thehandle 12, and in this embodiment is located diametrically opposite tothe male connector 38. The handle fluid outlet port 120 is alsoangularly spaced from the drive unit coupling member 70. The cleaningtool 14 comprises a cleaning tool fluid inlet port 224 for receivingworking fluid from the handle fluid outlet port 120. The cleaning toolfluid inlet port 224 is preferably in the form of a male connector whichis received by the handle fluid outlet port 120. Alternatively, thecleaning tool fluid inlet port 224 may be in the form of a femaleconnector, and the handle fluid outlet port 120 may be in the form of amale connector which is received by the cleaning tool fluid inlet port224.

The cleaning tool fluid inlet port 224 provides a fluid inlet of thecleaning tool conduit system 118. The fluid outlet 102 of the nozzle 36provides a fluid outlet of the cleaning tool conduit system 118. Withreference to FIGS. 17 and 18, the cleaning tool conduit system 118comprises a plurality of conduits for conveying working fluid from thecleaning tool fluid inlet port 224 to the nozzle 36. In this embodiment,the cleaning tool conduit system comprises a relatively rigid, firstfluid conduit 230, preferably formed from plastics or metallic material,and relatively flexible, second fluid conduit 232, preferably formedfrom resilient elastic material, for example PVC.

The second fluid conduit 232 extends between the first fluid conduit 230and the cleaning tool fluid inlet port 224. The first fluid conduit 230comprises an elongate first section 234 which extends within the stem26, adjacent to the connecting rod 82, and a second section 236. One endof the first section 234 is connected to the second fluid conduit 232,and the other end of the first section 234 is connected to the secondsection 236 of the first fluid conduit 230. The second section 236 isangled to the first section 234, and in this embodiment is in the formedof a curved conduit section which curves at an angle of around 90° toconvey working fluid into the nozzle 36. The nozzle 36 is connected tothe second section 236 of the first fluid conduit 230.

The first fluid conduit 230 is connected to a relatively rigid support240. The support 240 is in turn connected to a support mount 242, whichis held in a fixed position within, and relative to, the stem 26. Thesupport 240 is movable relative to the support mount 242, and thusrelative to the stem 26. In this embodiment, the support 240 isconnected to the support mount 242 for pivoting movement about pivotaxis P1. Pivot axis P1 passes through the stem 26, and is substantiallyorthogonal to the longitudinal axis Y of the cleaning tool 14.

The first fluid conduit 230 is thus pivotable relative to the stem 26 ofthe cleaning tool 14, and thus also pivotable relative to the handle 12.A guide member 244 is connected to the support mount 242 to guide thepivoting movement of the first fluid conduit 230 relative to the stem26. In view of the connection of the nozzle 36 to the first fluidconduit 230, any movement of the first fluid conduit 230 relative to thestem 26 causes the nozzle 36 to move with the first fluid conduit 230.This, in turn, results in movement of the nozzle 36 relative to thebrush unit 29 connected to the stem 26. In this embodiment, the firstfluid conduit 230 is shaped so that pivoting movement of the first fluidconduit 230 about the pivot axis P1 causes the nozzle 36 to moverelative to the brush unit 29 along a circular path which extends aboutthe pivot axis P1.

The nozzle 36 is moveable relative to the brush unit 29 between a first,or distal, position relative to the brush unit 29, and a second, orproximal, position relative to the brush unit 29. In the distalposition, the tip of the nozzle 36 protrudes outwardly beyond the endsof the bristles 32, whereas in the proximal position, the tip of thenozzle 36 is retracted relative to the ends of the bristles 32.

The guide member 244 may comprise stop members for inhibiting themovement of the nozzle 36 beyond the distal position, as shown in FIG.19(a), and the proximal position, as shown in FIG. 19(b). The distancetravelled by the tip of the nozzle 36 as the nozzle 36 moves from thedistal position to the proximal position is preferably in the range from1 to 5 mm, and in this embodiment is around 3 mm. When the nozzle 36 isin its distal position, the nozzle axis Z is preferably substantiallyorthogonal to the longitudinal axis Y of the cleaning tool 14. As thefirst fluid conduit 230 is pivotable about pivot axis P1, the tip of thenozzle 36 moves relative to the brush unit 29 in a circular path whichhas a centre which passes through the pivot axis P1. The angularmovement of the tip of the nozzle 36 about the pivot axis P1 as thenozzle 36 moves from the distal position to the proximal position ispreferably around 2.5°.

The first fluid conduit 230 is biased for movement about the pivot axisP1 in such a direction that urges the nozzle 36 towards the distalposition relative to the brush unit 29. A separate biasing member may belocated within the stem 26 for urging the first fluid conduit 230, orthe support 240, to pivot in that direction relative to the pivot axisP1. In this embodiment, the first fluid conduit 230 is urged to move inthat direction by the second fluid conduit 232. As mentioned above, thesecond fluid conduit 232 is preferably formed from resilient material,and so may be connected between the first fluid conduit 230 and thecleaning tool fluid inlet port 224 in an elastically deformedconfiguration. One end of the second fluid conduit 232 is held in afixed position relative to the stem 26 by the cleaning tool fluid inletport 224. The cleaning tool fluid inlet port 224 is, in turn, connectedto the support mount 242 by a connector 246 to which the second contrategear 76 is mounted for rotational movement relative thereto. The otherend of the second fluid conduit 232, which is connected to the firstfluid conduit 230, is free to move relative to the stem 26. The internalforce created within the elastically deformed second fluid conduit 232acts in such a direction as to urge that moveable end of the secondfluid conduit 232 to move relative to the fixed end of the second fluidconduit 232. This in turn urges the first fluid conduit 230 to pivot inthe aforementioned direction relative to the pivot axis P1 that urgesthe nozzle 36 towards the distal position relative to the brush unit 29.

A sensor 250 is provided for detecting movement of the support 240, andthus movement of the first fluid conduit 230 and the nozzle 36 whichmove with the support 240, relative to the handle 12 and the stem 26 ofthe cleaning tool 14. The sensor 250 is connected to the control circuit58. In this embodiment, the sensor 250 is in the form of a Hall effectsensor which detects the movement of a magnet 252 connected to thesupport 240, and which generates an output having a voltage which isdependent on the relative positions of the sensor 250 and the magnet252. The control circuit 58 is configured to receive the output from thesensor 250, and to sample that output every 10 ms, or at a frequency of100 Hz, to generate a sampled output, or sampled voltage, S, every 10ms.

From the sampled outputs received every 10 ms, the control circuit 58 isconfigured to generate the rate of change, Sr, of the sampled outputsfrom the difference between consecutive sampled outputs. Thus, thecontrol circuit is configured to calculate a value for Sr every 10 ms.

The control circuit is further configured to determine an average rateof change of the sensor output, Sa, by calculating the average value ofthe 10 most recent values of Sr. A value for Sa is thus also calculatedevery 10 ms from the values of Sr calculated during the preceding 100 mstime period.

The magnet 252 is connected to an arm 254, which is in turn connected tothe support 240. The arm 254 comprises a first end 256 which is insertedinto a socket 258 formed in the support 240 so that the first end 256 ofthe arm 254 is rotatable within the socket 258. The magnet 252 isconnected to the second end 260 of the arm 256. The length of the arm256 is chosen so that the magnet 252 is located adjacent to the endsurface of the cleaning tool 14 which faces the handle 12 when thecleaning tool 14 is connected to the handle 12. This can allow thesensor 250 to be located in the handle 12, and thus facilitate theconnection of the sensor 250 to the control circuit 58.

The arm 254 is preferably pivotable relative to the support 240 about asecond pivot axis P2. The second pivot axis P2 is spaced from, andsubstantially parallel to, the pivot axis P1. The second pivot axis P2passes through the socket 258 into which the first end 256 of the arm254 is connected so that a given movement of the first end 256 of thearm 254, through movement of the support 240 about the pivot axis P1,results in a greater movement of the second end 260 of the arm 254 aboutthe second pivot axis P2. This serves to amplify the movement of themagnet 252 relative to the sensor 250, in comparison to the movementthat would be produced were the magnet 252 connected directly to thesupport 240. The movement of the arm 256 about the second pivot axis P2is guided by a pair of constraints 262 between which the arm 256 islocated, and which are connected to the stem 26.

In use, the user first fills the fluid reservoir 34 with working fluid,which in this embodiment is water. As shown in FIG. 20, the user mayplace the appliance 10 beneath the spout of a tap and turn on the tap sothat water from the spout enters the recessed portion 126 of the body 16of the handle 12. With the collar 124 in the first position so that thefluid port 122 is exposed, the curved wall 128 guides water through thefluid port 122 and into the fluid reservoir 34. As the external wall 132of the fluid reservoir 34 is transparent, the user can observe thefilling of the fluid reservoir 34, and the contraction of the inner wall138 of the fluid reservoir 34 under the weight of the water within thefluid reservoir 34. As the fluid reservoir 34 becomes filled with water,air is expelled from the expansion chamber 148. When the fluid reservoir34 is full, the user moves the collar 124 to the second position toconnect the fluid port 122 to the fluid inlet 104 of the fluid deliverysystem 100.

The user switches on the appliance 10 by depressing button 22, theaction of which is detected by the control circuit 58. The user can thenselect a mode of operation of the appliance 10 by depressing button 20.The currently selected mode of operation of the appliance 10 isdisplayed on the display 24, and the user can toggle between the variousselectable modes of operation by depressing button 20 until the desiredoperational mode is displayed on the display 24. In this embodiment,there are six different user selectable operational modes:

MODE BRUSHING MANUAL JET AUTO JET 1 ON OFF OFF 2 ON ON OFF 3 ON OFF ON 4OFF ON OFF 5 OFF OFF ON 6 ON ON ON

When any of modes 1 to 3 or 6 are selected, the control circuit 58activates the motor 56 to move the brush unit 29 relative to the handle12 to brush teeth 300, shown in FIG. 21, against which the brush unit 29is pressed by the user. The drive mechanism 50 and the motor 58 areconfigured to generate a movement of the bristle carrier 30 about thenozzle 36 in the range from 4,000 to 6,000 revolutions per minute, whereeach revolution is a single 360° rotation of the crank 78, and thus asingle 360° orbital movement of the bristle carrier 30 about the nozzle36.

When any of modes 2 to 6 are selected, initially the control circuit 58operates the pump 106 to charge the accumulator 108. With the solenoidvalve 114 in a closed position, the pump 106 is operated for a period oftime, in this embodiment around 500 ms, to draw a volume of water fromthe fluid reservoir 34, and to convey that volume of drawn water to theaccumulator 108. In this embodiment, the volume of water which is drawnfrom the fluid reservoir 34 each period of time that the pump 106 isoperated is around 0.25 ml. When that volume of water is received by theaccumulator 108, the pressure of water within the fluid chamber 182 ofthe accumulator 108 is around 5.5 bar (around 550 kPa). The pump 106 maybe deactivated by the control circuit 58 upon expiry of that period oftime, or in response to the receipt of an output generated by the sensorlocated in the accumulator 108. Following delivery of that volume ofwater to the accumulator 108, the second one-way valve 112 is in aclosed position to prevent water from returning to the pump 106 from theaccumulator 108.

When mode 2, mode 4 or mode 6 is selected by the user, a burst of wateris emitted from the nozzle 36 in response to user depression of thebutton 18. The depression of the button 18 is detected by the controlcircuit 58. The control circuit 58 activates the coil 216 of thesolenoid valve 114 to move the solenoid valve 114 to the open position.This allows the piston 186 of the accumulator 108 to move rapidlytowards the fluid port 180 to urge the volume of water out from theaccumulator 108 in the form of a pressurised burst of water. The timetaken to urge that volume of water from the accumulator 108 ispreferably in the range from 1 to 50 ms, and in this embodiment isaround 30 ms. The burst of water passes though the solenoid valve 114and the cleaning tool conduit system 118 to be ejected from the fluidoutlet of the nozzle 36. When the nozzle 36 is positioned within oraligned with an interproximal gap, the burst of water ejected from thenozzle 36 can dislodge matter located within the interproximal gap.

The control circuit 58 is arranged to replenish the accumulator 108following the delivery of the burst of water to the cleaning toolconduit system 118. The control circuit 58 is arranged to move thesolenoid valve 114 to the closed position, and to operate the pump 106to convey another volume of water from the fluid reservoir 34 to theaccumulator 108. The control circuit 58 is configured to disable theopening of the solenoid valve 114, in response to the user depression ofthe button 18, until the accumulator 108 has become fully replenishedwith water, and so for a period of around 500 ms after the last burst ofwater was ejected from the nozzle 36.

When mode 3, mode 5 or mode 6 is selected by the user, a burst of wateris emitted from the nozzle 36 depending on an output from the sensor250. Thus, when mode 6 is selected, a burst of water is emitted from thenozzle 36 depending on an output from the sensor 250 or in response touser depression of the button 18. FIGS. 21(a) to 21(f) illustrateschematically the use of the appliance 10 to clean a user's teeth 300.As the brush unit 29 is moved across the user's teeth, the tip of thenozzle 36 engages the user's teeth. The force that is applied to thenozzle 36 as the nozzle 36 is pushed against the user's teeth overcomesthe biasing force applied to the first fluid conduit 230 by the secondfluid conduit 232, and so the nozzle 36 moves away from the distalposition towards its proximal position. As the brush unit 29 is movedacross, for example, tooth 302, the position of the nozzle 36 relativeto the stem 26 will vary depending on the contours of the tooth 302 andthe force with which the head 28 is pressed against the tooth 302.

The control circuit 58 is initially in a first, or “unprimed”,condition. As the brush unit 29 passes from tooth 302 to the adjacenttooth 304, the nozzle 306 becomes positioned over the interproximal gapbetween those teeth, as shown in FIG. 21(c). In that position, the forceacting on the nozzle 36, through its engagement with the teeth of theuser, is removed. This allows the second fluid conduit 232 to urge thefirst fluid conduit 230 to pivot about the pivot axis P1, which movesthe nozzle 36 rapidly towards its distal position. This movement of thefirst fluid conduit 230 about the pivot axis P1 causes the support 240to move relative to the support mount 242, which in turn causes themagnet 252 to move rapidly, relative to the sensor 250, towards theposition shown in FIG. 19(a).

This generates a rapid variation in the signal output from the sensor250 to the control circuit 58, and thus a relatively large change in thevalue of Sa calculated by the control circuit 58. In this embodiment, Sahas a relatively large negative value when the nozzle 36 moves rapidlytowards its distal position. When the value of Sa falls below a firstthreshold value, which occurs when the tip of the nozzle 36 enters aninterproximal gap, the control circuit 58 enters a second, or “primed”,condition.

With the tip of the nozzle 36 now located within the interproximal gap,the value of Sa increases rapidly. This can be to a value ofapproximately zero, or to a value greater than zero as the nozzle 36moves away its distal position as the tip of the nozzle 36 begins tomove over the tooth 304.

When the value of Sa subsequently rises above a second threshold value,which is greater than the first threshold value, the control circuit 58enters a third, or “ejection”, condition in which the control circuit 58activates the coil 216 of the solenoid valve 114 to open the solenoidvalve 114. As described above, the opening of the solenoid valve 114causes a burst of water, as identified at 306 in FIG. 21(e), to beejected from the nozzle 36 into the interproximal gap between the teeth.

Following the delivery of the burst of water to the cleaning toolconduit system 118, the control circuit 58 is arranged to replenish theaccumulator 108. The control circuit 58 is arranged to move the solenoidvalve 114 to the closed position, and to operate the pump 106 to conveyanother volume of water from the fluid reservoir 34 to the accumulator108. The control circuit 58 is configured to disable the opening of thesolenoid valve 114 in response to the output received from the sensor250, until the accumulator 108 has become fully replenished with water,and so for a period of around 500 ms after the last burst of water wasejected from the nozzle 36. Once the accumulator 108 has beenreplenished, the control circuit 58 returns to its first, or “unprimed”,condition.

The appliance 10 may be configured to reduce the risk of undesiredejection of bursts of working fluid when the nozzle 36 is not locatedwithin an interproximal gap of the user, for example during handling ofthe appliance 10, when any of mode 2, mode 3 or mode 6 has been selectedby the user. In each of these modes, the motor 56 is activated to movethe bristle carrier 30 relative to the handle 12. To maintain a constantspeed of movement of the bristle carrier 30 relative to the handle 12,the motor 56 may draw a variable amount of current, the magnitude of thedrawn current varying as a resistance is applied to the motion of thebrush unit 29 about the nozzle 36. The magnitude of the current drawn bythe motor 56 can thus provide an indication that the brush head 29 isbeing pressed against a user's teeth.

The control circuit 58 may be configured to monitor the current which isdrawn by the motor 56. When the current drawn by the motor 56 is below apre-set threshold value, this can provide an indication that the brushunit 29 is not being used to clean a user's teeth, for example, when theappliance 10 has first been switched on by the user, or if the fluidreservoir 34 is being replenished by the user while the appliance 10 isswitched on. In this event, the appliance 10 enters a first operationalmode, in which the delivery of a burst of water to the teeth of a useris inhibited, irrespective of whether the button 18 is depressed (inmode 2 or mode 6) or the output from the sensor 250 (in mode 3 or mode6).

When the current drawn by the motor 56 is above the pre-set thresholdvalue, this can provide an indication that the brush unit 29 is beingused to clean a user's teeth. In this event, the appliance 10 enters asecond operational mode, in which the delivery of a burst of water tothe teeth of a user is permitted. The current drawn by the motor 56 iscontinuously monitored by the control circuit 58, and the controlcircuit 58 is arranged to effect a transition between the firstoperational mode and the second operational mode automatically as thedetected current falls below, or rises above, the threshold value.

A second, higher, threshold value may also be pre-set in the controlcircuit 58. When the current drawn by the motor 56 exceeds this secondthreshold value, the control circuit 58 may generate an alert, forexample, an audible alert or a visual alert displayed on the display 24,to warn the user that the brush unit 29 is being pressed too firmlyagainst the user's teeth.

In the above embodiment, the capacity of the fluid chamber 182 of theaccumulator 108 is substantially the same as the volume of a singleburst of working fluid. However, the capacity of the fluid chamber 182may be larger than the volume of a single burst of working fluid.

In a second embodiment, the fluid chamber has a capacity of 0.75 ml, anda single burst of working fluid has a volume of around 0.25 ml. In thissecond embodiment, when in its third condition the control circuit 58 isarranged to hold the solenoid valve 114 in an open position for a timeperiod which allows only the required volume of working fluid to beejected from the accumulator 108 to form a single burst of workingfluid. For example, the solenoid valve 114 may be held in an openposition for a time period of 30 ms to allow a single burst of workingfluid having a volume of 0.25 ml to be delivered to the nozzle 36. Thecontrol circuit 58 returns to its first condition following the ejectionof that single burst of working fluid. In this case, and provided thatthere is sufficient working fluid in the accumulator 108 to deliverthose three bursts of working fluid to the nozzle 36, the controlcircuit 58 is arranged to replenish the accumulator 108 following thedelivery of every third burst of working fluid to the cleaning toolconduit system 118.

In a third embodiment, the fluid chamber has a capacity of 0.25 ml, anda single burst of working fluid has a volume of around 0.08 ml. Similarto the second embodiment, in this third embodiment the control circuit58 is arranged to hold the solenoid valve 114 in an open position for atime period which allows only the required volume of working fluid to beejected from the accumulator 108 to form a single burst of workingfluid. For example, the solenoid valve may be held in an open positionfor a time period of around 10 ms to allow a single burst of workingfluid having a volume of 0.08 ml to be delivered to the nozzle 36.Again, in this case the control circuit 58 is arranged to replenish theaccumulator 108 following the delivery of every third burst of workingfluid to the cleaning tool conduit system 118, but the time required toreplenish the accumulator 108 in this third embodiment is shorter thanthe time required to replenish the accumulator 108 in the secondembodiment.

In each of the first to third embodiments, the control circuit 58 isarranged to deliver a single burst of working fluid depending on areceived input, which is either an output from the sensor 250, or a useraction on the appliance 10, such as the depression of the button 18.However, the control circuit 58 may be arranged to deliver a series ofbursts of working fluid depending on such a received input. Each of thebursts of working fluid within a series preferably containssubstantially the same volume of working fluid.

In a fourth embodiment, the fluid chamber 182 of the accumulator 108 hasa capacity of 0.25 ml, and the control circuit 58 is arranged to controlthe fluid delivery system 100 to deliver a single series of three burstsof working fluid, each having a volume of around 0.08 ml, in response touser depression of the button 18, or depending on the output from thesensor 250, depending on whichever one of modes 2 to 6 has been selectedby the user.

For example, when either mode 2 or mode 4 is selected by the user aseries of bursts of water is emitted from the nozzle 36 in response touser depression of the button 18. The depression of the button 18 isdetected by the control circuit 58. The control circuit 58 activates thecoil 216 of the solenoid valve 114 to move the solenoid valve 114 to theopen position. The control circuit 58 holds the solenoid valve 114 inthe open position only for a time period which allows the piston 186 ofthe accumulator 108 to urge a volume of water from the accumulator 108to form the first pressurised burst of water. In this embodiment, thetime taken to urge that volume of water from the accumulator 108 isaround 10 ms, and so after that period of time the control circuit 58deactivates the coil 216 of the solenoid valve 114 to allow the solenoidvalve 114 to move to the closed position.

Once the solenoid valve 114 is in the closed position, the controlcircuit 58 re-activates the coil 216 of the solenoid valve 114 to movethe solenoid valve 114 back to the open position. Again, the controlcircuit 58 holds the solenoid valve 114 in the open position only for atime period which allows the piston 186 of the accumulator 108 to urge asecond volume of water from the accumulator 108 to form the secondpressurised burst of water, and so in this embodiment a second timeperiod of around 10 ms.

After that period of time has elapsed, the control circuit 58deactivates the coil 216 of the solenoid valve 114 to allow the solenoidvalve 114 to move to the closed position. Once the solenoid valve 114 isin the closed position, the control circuit 58 again re-activates thecoil 216 of the solenoid valve 114 to move the solenoid valve 114 backto the open position. Once again, the control circuit 58 holds thesolenoid valve 114 in the open position only for a time period whichallows the piston 186 of the accumulator 108 to urge a third volume ofwater from the accumulator 108 to form the third pressurised burst ofwater, and so in this embodiment a third time period of around 10 ms.After that period of time has elapsed, the control circuit 58deactivates the coil 216 of the solenoid valve 114 to allow the solenoidvalve 114 to move to the closed position. The pump 106 is then operatedto replenish the accumulator 108.

Within a series, the time period between successive bursts of workingfluid is preferably equal, and is preferably in the range from 1 to 25ms, more preferably in the range from 2 to 10 ms, so that the entireseries of bursts may be delivered to a single interproximal gap. Thiscan allow for a slight variation in the position of the tip of thenozzle 36 relative to interproximal gap with each successive burst, andso potentially improving the removal of material from within theinterproximal gap.

In this fourth embodiment, the capacity of the fluid chamber 182 of theaccumulator 108 is substantially the same as the volume of working fluidwhich is ejected from the nozzle 36 in a single series of bursts ofworking fluid. Alternatively, the capacity of the fluid chamber 182 ofthe accumulator 108 may be greater than the volume of working fluidwhich is ejected from the nozzle 36 in a single series of bursts ofworking fluid. For example, in a fifth embodiment, the capacity of thefluid chamber 182 is increased to 0.75 ml, but the control circuit 58 isarranged to eject the same, single series of three bursts of workingfluid, each having a volume of around 0.08 ml, in response to userdepression of the button 18, or depending on the output from the sensor250. Therefore, in this fifth embodiment the accumulator 108 requiresreplenishment following the delivery of three series of bursts ofworking fluid from the appliance 10.

The invention claimed is:
 1. A dental cleaning appliance comprising: ahandle; a fluid delivery system for delivering a burst of working fluidto teeth of a user, the fluid delivery system comprising a nozzle fromwhich the burst of working fluid is delivered to the teeth of the user;a brush unit comprising a bristle carrier and a plurality of bristlesmounted on the bristle carrier, the brush unit extending at leastpartially about the nozzle, the nozzle being moveable relative to thebrush unit between a distal position and a proximal position; a stemextending between the brush unit and the handle; and a drive unit fordriving movement of the bristle carrier relative to the nozzle and thestem, the drive unit comprising a motor.
 2. The appliance of claim 1,wherein the brush unit surrounds the nozzle.
 3. The appliance of claim1, wherein the bristle carrier is annular in shape.
 4. The appliance ofclaim 1, wherein the nozzle extends along a nozzle axis, and wherein thebristle carrier is moveable about the nozzle axis.
 5. The appliance ofclaim 1, wherein the nozzle is biased in a direction extending away fromthe brush unit.
 6. The appliance of claim 1, wherein the fluid deliverysystem comprises a fluid conduit for conveying the burst of workingfluid to the nozzle, and wherein the fluid conduit is moveable relativeto the handle.
 7. The appliance of claim 6, wherein the fluid conduit ismoveable with the nozzle.
 8. The appliance of claim 7, wherein the fluidconduit is connected to or engages the nozzle.
 9. The appliance of claim1, wherein, when the nozzle is in the distal position, a tip of thenozzle protrudes beyond at least some free ends of the bristles.
 10. Theappliance of claim 1, wherein the fluid delivery system comprises asource of pressurized working fluid located in the handle, and a controlcircuit for actuating the delivery of the burst of working fluid fromthe source.
 11. The appliance of claim 1, wherein the working fluid is aliquid working fluid.
 12. The appliance of claim 1, wherein the fluiddelivery system comprises a pump located in the handle.
 13. Theappliance of claim 1, wherein the bristle carrier is moveable in anorbital path about the nozzle.
 14. The appliance of claim 13, whereinthe nozzle is located at a centre of the orbital path.
 15. The applianceof claim 13, comprising a transmission unit for converting a rotarymotion generated by the drive unit into an orbital motion of the bristlecarrier.
 16. The appliance of claim 15, wherein the transmission unitcomprises a set of gears which is connected to the drive unit, a crank,and a connecting rod which connects the bristle carrier to the crank.17. The appliance of claim 16, wherein the transmission unit is locatedin the stem.
 18. The appliance of claim 1, comprising a head, whereinthe stem extends between the head and the handle, and wherein the headcomprises the nozzle and the brush unit.
 19. The appliance of claim 1,wherein a cleaning tool of the appliance comprises the brush unit andthe cleaning tool comprises a fluid reservoir for storing the workingfluid.
 20. The appliance of claim 1, wherein a cleaning tool of theappliance comprises the brush unit and the cleaning tool is detachablyconnected to the handle.
 21. The appliance of claim 1, wherein the driveunit comprises a set of gears.
 22. A cleaning tool for a dental cleaningappliance comprising a handle to which the cleaning tool is detachablyconnectable, the handle comprising a drive unit, the drive unitcomprising a motor and a drive unit coupling member; the cleaning toolcomprising: a cleaning tool conduit system comprising a nozzle fordelivering a burst of working fluid to teeth of a user; a brush unitcomprising a bristle carrier and a plurality of bristles mounted on thebristle carrier, the brush unit extending at least partially about thenozzle, the nozzle being moveable relative to the brush unit between adistal position and a proximal position; a stem extending from the brushunit so that the stem extends between the brush unit and the handle whenthe cleaning tool is connected to the handle; and a transmission unitconnected at one end to the bristle carrier and comprising atransmission unit coupler for coupling with the drive unit couplingmember when the cleaning tool is connected to the handle so that thedrive unit can drive the bristle carrier relative to the nozzle and thestem.
 23. The cleaning tool of claim 22, wherein the brush unitsurrounds the nozzle.
 24. The cleaning tool of claim 22, wherein thebristle carrier is annular in shape.
 25. The cleaning tool of claim 22,wherein the nozzle extends along a nozzle axis, and wherein the bristlecarrier is moveable about the nozzle axis.
 26. The cleaning tool ofclaim 22, wherein the nozzle is biased in a direction extending awayfrom the brush unit.
 27. The cleaning tool of claim 22, wherein thecleaning tool conduit system comprises a fluid conduit for conveying theburst of working fluid to the nozzle, and wherein the fluid conduit ismoveable relative to the brush unit.
 28. The cleaning tool of claim 27,wherein the fluid conduit is moveable with the nozzle.
 29. The cleaningtool of claim 28, wherein the fluid conduit is connected to or engagesthe nozzle.
 30. The cleaning tool of claim 22, wherein, when the nozzleis in the distal position, a tip of the nozzle protrudes beyond at leastsome free ends of the bristles.
 31. The cleaning tool of claim 22,wherein the bristle carrier is moveable in an orbital path about thenozzle.
 32. The cleaning tool of claim 31, wherein the nozzle is locatedat a centre of the orbital path.
 33. The cleaning tool of claim 22,wherein the transmission unit comprises a set of gears which isconnected to the drive unit, a crank, and a connecting rod whichconnects the bristle carrier to the crank.
 34. The cleaning tool ofclaim 22, comprising a head and the head comprises the nozzle and thebrush unit.
 35. The cleaning tool of claim 34, wherein the transmissionunit is located in the stem.
 36. The cleaning tool of claim 22,comprising a fluid reservoir for storing working fluid.